Archive. ECDC and EuroFlu Influenza Updates, 2011.

[Giuseppe]

Weekly influenza surveillance overview, March 18, 2011 - Week 10 - 18 Mar 2011 (ECDC, edited)

Weekly influenza surveillance overview, March 18, 2011 - Week 10 - 18 Mar 2011 (ECDC, edited)


[Source: European Centre for Disease Prevention and Control (ECDC), full page: <cite cite="http://www.ecdc.europa.eu/en/publications/Publications/Forms/ECDC_DispForm.aspx?ID=659">Publications - 180311_SUR_Weekly_Influenza_Surveillance_Overview. pdf...</cite>. Edited.]

Weekly influenza surveillance overview, March 18, 2011 - Week 10 - 18 Mar 2011

Available as PDF in the following languages: English.

This document is free of charge.


ABSTRACT

The majority of European countries reported decreasing ILI/ARI trends.

Most countries reported some regional or sporadic influenza activity.

• In week 10/2011, the proportion of influenza B viruses (58.9%) in sentinel specimens was higher than the percentage of influenza A viruses (41.1%).
• Thirty-two (3.0%) of influenza A(H1) 2009 viruses tested for susceptibility were resistant to oseltamivir but remained sensitive for zanamivir.
• All the resistant viruses carried the H275Y mutation.
• In week 10/2011, five countries reported 39 cases of all-cause severe acute respiratory infection (SARI) and 43 hospitalised confirmed influenza cases.
• The latter were mostly (68.4%) due to influenza A(H1N1)2009 virus infection.

-
-----

[Giuseppe]

EpiSouth Weekly Epi Bulletin ? N?156 - 9th March 2011 ? 15th March 2011 (Extract, edited)

EpiSouth Weekly Epi Bulletin ? N?156 - 9th March 2011 ? 15th March 2011 (Extract, edited)


[Source: EpiSouth, full PDF document (LINK). Extract, edited.]

EpiSouth Weekly Epi Bulletin ? N?156 - 9th March 2011 ? 15th March 2011

The objective of the bulletin is to report new heath events occurring outside and inside EpiSouth area that have potential implications on EpiSouth population. It does not aim to provide an exhaustive review of international alerts. Since 2006, The French public health Institute (InVS) is issuing an online epidemic intelligence bulletin (Bulletin hebdomadaire International - BHI). In order to limit duplication and to make this already verified information available to a larger audience, information relating to health events of interest for EpiSouth population are translated and integrated in the relevant e-web sections. Despite all verifications, WP6 team would not be responsible for potential errors. The recipient is responsible for the cautious use of this information. Neither the European Commission nor any person acting on behalf of the Commission is liable for the use that may be made of the information contained in this report. Data maps and commentary used in this document do not imply any opinion of EpiSouth countries or its partners on the legal status of the countries and territories shown or concerning their borders.


INDEX e-WEB n?156

• A(H5N1) Human influenza ? Egypt, Indonesia, Bangladesh
• A(H5N1) Avian influenza ? no new events
• ?INSIDE? Events: none
• ?OUTSIDE? events: none

Location: Egypt, Indonesia, Bangladesh - Event: A(H5N1) ? Human

EGYPT

• On 12th March 2011, the Egyptian Ministry of Health reported 2 new human A(H5N1) cases in Behera and Ismailia governorates (cf. map 1).
• The 129th case is:
  • A 17 years old female from Behera governorate
  • Onset of symptoms on 27th February 2011
  • She was hospitalized on 1st March 2011
• The 130th case is:
  • A 38 years old female from Ismailia governorate
  • Onset of symptoms on 1st March 2011
  • She was hospitalized on 7th March 2011
  • She died on 11th March 2011
• To date, a total of 130 A(H5N1) cases and 44 deaths have been reported in Egypt.
• In Egypt, the last A(H5N1) human case was reported on 5th March 2011 (cf. eWEB n?155).

INDONESIA

• On 14th March 2011, the Indonesian health authorities reported to WHO 2 new human A(H5N1) cases in West Java province (cf. map 2).
• The first case is:
  • A 2 years old boy
  • Onset of symptoms on 3rd February 2011
  • Hospitalized on 5th February 2011
  • He died on 6th February 2011
• The second case is:
  • A 31 years old female
  • Onset of symptoms on 23rd February 2011
  • Hospitalized on 25th February 2011
  • She died on 1st March 2011
• For both cases, contacts with contaminated domestic birds has been documented.
• In Indonesia, the last A(H5N1) human case was reported on 2nd March 2011, in the same province (cf. eWEB n? 155).

Comments

• The A(H5N1) is enzootic in Indonesia.
• To date, 174 A(H5N1) cases including 144 deaths were reported to WHO in Indonesia.
• In the country, suspected A(H5N1) cases are regularly reported by various non official sources. In this respect, it is likely that the number of cases is under reported by national authorities.

BANGLADESH

• On 14th and 16th March 2011, the Bangladeshi Institute of Epidemiology, Disease Control and Research reported two new human A(H5N1) cases in Kamalapur area, in Dakha capital (cf. map 3). They are the first reported A(H5N1) cases this year, bringing the total number of cases to 3 since 2008.
• The first case, reported on 14th March 2011, is :
  • A 13 months old girl
  • Hospitalised in Dakha
  • An exposure to a slaughtered chicken has been documented
• The second case, reported on 16th March 2011 is :
  • A 31 months old boy
  • There is no information on contacts with domestic birds
  • To date, there is no link between these 2 cases.

Comments

• The last human case in the country was reported on May 2008, in the Dakha province (cf. eWEB n?10).
• Since January 2011, several A(H5N1) epizooties are reported in the country, including Dakha province (cf. eWEB n?147).

-
-----

[Giuseppe]

EuroFlu - Weekly Electronic Bulletin - Week 11 : 14/03/2011-20/03/2011 - 25 March 2011, Issue N? 395 (extract, edited)

EuroFlu - Weekly Electronic Bulletin - Week 11 : 14/03/2011-20/03/2011 - 25 March 2011, Issue N? 395 (extract, edited)


[Source: EuroFlu, full page: <cite cite="http://www.euroflu.org/cgi-files/bulletin_v2.cgi">EuroFlu - Bulletin Review</cite>. Extract, edited.]

EuroFlu - Weekly Electronic Bulletin - Week 11 : 14/03/2011-20/03/2011 - 25 March 2011, Issue N? 395

Influenza activity declining in the WHO European Region

• This issue is based on data reported in week 11/2011 by 46 Member States in the WHO European Region.
• Influenza-like illness (ILI) and acute respiratory infection (ARI) activity has passed recent peaks in 38 countries of the Region.
• Sentinel hospitalizations for severe acute respiratory infections (SARI) are generally declining, but remain above pre-season levels in some countries.
• 33% of sentinel specimens from patients with ILI and/or ARI, and 40% of specimens from sentinel SARI patients tested positive for influenza.
• Pandemic influenza A(H1N1) 2009 and influenza B continue to co-circulate in the Region.

Current situation - week 11/2011

During week 11/2011, 23 countries reported a low intensity of influenza and 17 countries reported medium intensity.

Among 40 countries reporting on the geographical spread of influenza, a majority reported either sporadic (20) or local (9) activity, while 10 reported either regional or widespread activity and one country reported no activity.

The impact of influenza on health care systems was low in 21 and moderate in 4 of the 25 countries reporting on this indicator.

Clinical data also suggest decreasing influenza activity in much of the WHO European Region.

Of the 39 countries reporting on consultation rates for ILI and/or ARI, 21 countries reported decreases and 38 have passed apparent peaks in ILI or ARI clinical activity.

Data from sentinel hospital-based surveillance for SARI were received from 10 countries (Armenia, Georgia, Kazakhstan, Kyrgyzstan, Malta, the Republic of Moldova, Romania, the Russian Federation, Serbia and Ukraine).

During week 11/2011, sentinel SARI hospitalizations were higher than the previous week in the Republic of Moldova and Romania but remain below previously observed peak levels for this season.

In Armenia, Georgia, Serbia and Ukraine, SARI hospitalizations have decreased compared to recent weeks, but they still remain above pre-season levels.

SARI hospitalizations were stable and generally low in Kazakhstan, Malta and the Russian Federation.

In the 5 countries (Georgia, Kazakhstan, Romania, the Russian Federation and Ukraine) testing 10 or more sentinel SARI specimens, the percentage testing positive for influenza ranged from 15% in Kazakhstan to 58% in Ukraine.

Further information on the sentinel SARI surveillance systems represented in the EuroFlu bulletin can be found in the Overview of sentinel SARI systems in EuroFlu.


Virological situation - week 11/2011

Pandemic influenza A(H1N1) 2009 was reported to be dominant in 9 countries and co-dominant with influenza B in 10 countries.

Influenza B was dominant in 6 countries.

Sentinel physicians collected 912 respiratory specimens, of which 298 (33%) were positive for influenza virus: 89 (30%) were influenza A and 209 (70%) were influenza B.

Of the influenza A viruses, 82 were subtyped: 68 (83%) as pandemic A(H1) and 14 (17%) as A(H3).

In the 15 countries testing 20 or more sentinel specimens, influenza positivity ranged from 0% in France to 88% in Georgia, with a median of 31% (mean: 35%).

In addition, 1707 non-sentinel specimens were reported positive for influenza: 1117 (65%) influenza A and 590 (35%) influenza B.

Of the influenza A viruses, 999 were subtyped: 968 (97%) as pandemic A(H1) and 31 (3%) as A(H3).

Out of 155 sentinel SARI specimens collected during week 11/2011 (data from 9 countries), 62 (40%) tested positive for influenza: 37 (60%) were influenza A; 25 (40%) were influenza B.

Of the influenza A viruses, 23 were subtyped and all were pandemic A(H1).


Cumulative virological update - weeks 40/2010 - 11/2011

A total of 80 531 influenza virus detections were reported during this period, of which 57 673 (72%) were influenza A and 22 858 (28%) were influenza B.

Of the influenza A viruses, 45 626 were subtyped: 43 997 (96%) as pandemic A(H1), 1628 (4%) as influenza A(H3) and 1 as influenza A(H1).

From week 40/2010 to week 11/2011, 1400 out of 4424 sentinel SARI specimens (32%) tested positive for influenza.

Of these influenza viruses, 770 (55%) were influenza A and 630 (45%) influenza B.

Of the influenza A viruses, 505 were subtyped: 464 (92%) as pandemic A(H1) and 41 (8%) as influenza A(H3).

Since week 40/2010, 3699 influenza viruses have been characterized antigenically:

• 1837 were A(H1) pandemic A/California/7/2009 (H1N1)-like;
• 1615 were B/Brisbane/60/2008-like (B/Victoria/2/87 lineage);
• 113 were A(H3) A/Perth/16/2009 (H3N2)-like;
• 133 were B/Florida/4/2006-like (B/Yamagata/16/88 lineage); and
• 1 was B/Bangladesh/3333/2007-like (B/Yamagata/16/88 lineage).

Based on the genetic characterization of 519 influenza viruses:

• 215 belonged to the pandemic A/California/7/2009 A(H1N1) clade;
• 10 belonged to the pandemic A/Christchurch/16/2010 A(H1) clade;
• 46 belonged to the pandemic A/Hong Kong/2213/2010 A(H1) clade;
• 41 were reported as A(H1) pandemic not attributed to group category but belonging to the recently emerged A/England/142/2010 subgroup characterized by S185T substitution in the HA;
• 11 belonged to the A(H3) clade represented by A/Perth/16/2009;
• 7 belonged to the A(H3) clade represented by A/Victoria/208/2009;
• 30 belonged to the subgroup represented by A/Hong Kong/2121/2010 in the A/Victoria/208/2009 A(H3) clade;
• 19 belonged to the B/Bangladesh/3333/2007 clade (Yamagata lineage), and
• 140 to the B/Brisbane/60/2008 clade (Victoria lineage).

Since week 40/2010, 8 countries (Germany, Ireland, Italy, Netherlands, Norway, Spain, Switzerland and the United Kingdom) have screened 1444 viruses for susceptibility to the neuraminidase inhibitors oseltamivir and zanamivir.

The United Kingdom analysed most of the viruses screened (735).

Out of the 1333 pandemic A(H1N1) 2009 viruses that were tested, 1291 were sensitive to both inhibitors and 42 viruses (3.2%) carried the NA H275Y mutation.

These 42 viruses were resistant to oseltamivir but remained sensitive to zanamivir.

4 influenza A(H3N2) viruses were tested and found to be sensitive to both inhibitors.

All of the 107 influenza B viruses tested for susceptibility to oseltamivir and the 96 tested for susceptibility to zanamivir were found to be sensitive.

All 178 pandemic influenza A(H1N1) 2009 viruses and 2 A(H3N2) viruses that were screened for susceptibility to adamantanes were found to be resistant.


Comment

ILI and ARI consultation rates continue to decline throughout most parts of the WHO European Region with all countries reporting medium or low activity during week 11/2011.

Significant influenza activity continues in some places however.

The overall percentage of sentinel ILI, ARI and SARI specimens testing positive for influenza has declined from about 40% in previous weeks to 33% in week 11/2011.

The percentage of sentinel specimens testing positive was highest in weeks 4 and 5 (46%) and corresponded to the peak of clinical influenza activity, which occurred during weeks 4 to 6 in 26 out of 40 countries.

Influenza B and pandemic influenza A(H1N1) 2009 co-dominate in the Region.


Further information

The EuroFlu bulletin describes and comments on influenza activity in the 53 countries in the WHO European Region.

For an update on the influenza situation and WHO/Europe recommendations, see the WHO/Europe web site.

Further information can be obtained from the web sites of WHO/Europe, WHO headquarters and the European Centre for Disease Prevention and Control.

Further information on severe cases associated with influenza virus infections in the European Region can be found in the ECDC Weekly Influenza Surveillance Overview.

(...)


Network comments (where available)

• Malta
  • situation stable
• Republic of Moldova
  • One lethal case from influenza A(H1N1)2009 was registred in the 11th week
• Serbia
  • Serbia Sentinel SARI surveillance system in SERBIA: In week 11/2011, 19 SARI from all causes were reported.
  • Out of 13 SARI specimens collected in the week 11/2011, 4 (30.7%) tested positive: 2 were influenza A and 2 were influenza B.
• Spain
  • In Spain information concerning severe illness due to influenza infection with associated admission to hospitals comes from a surveillance system developed during the 2009/2010 pandemic season specifically for this purpose.
  • Since week 40/2010 and up to week 11/2011 1340 severe hospitalised confirmed influenza cases have been reported.
  • Severely affected cases were mostly in the 15-64 year age groups (63%) and 16% were less than five years old and 18% were more than 64 years old.
  • 25% of them with no known risk factors.
  • Of 1333 cases with outcome information 148 died (13% with no known risk factors).
  • Of the severe cases 873 had information available on the status of influenza vaccination for the 2010/2011 season and only 128 (15%) cases had been immunised.
  • Monovalent pandemic vaccines 2009 were reported to have been received for 9% of hospitalised cases.
  • Most of severe and fatal cases included in the groups which were recommended influenza vaccination had not been vaccinated this season

(...)
-
------

[Giuseppe]

Weekly influenza surveillance overview, March 25, 2011 - Week 11 (ECDC, edited)

Weekly influenza surveillance overview, March 25, 2011 - Week 11 (ECDC, edited)


[Source: European Centre for Disease Prevention and Control (ECDC), full page: <cite cite="http://www.ecdc.europa.eu/en/publications/Publications/Forms/ECDC_DispForm.aspx?ID=664">Publications - 110325_SUR_Weekly_Influenza_Surveillance_Overview. pdf...</cite>. Edited.]

Weekly influenza surveillance overview, March 25, 2011 - Week 11

Surveillance reports - 25 Mar 2011


Available as PDF in the following languages: English.

This document is free of charge.


ABSTRACT

In week 11/2011, 16 EU countries experienced influenza activity of low intensity and 22 countries reported stable or decreasing trends. Nevertheless, widespread activity was still reported by two countries. In week 11/2011, 46.1% of detected influenza viruses were of type A, and 53.9% were of type B. This latter virus was dominant in seven countries and co-dominant with influenza virus A(H1N1) 2009 in five countries. It was the first week of this season that the influenza B virus was overall dominant. Six countries notified 71 severe respiratory cases, of which 34 were infected by an influenza virus.

-
------

[Giuseppe]

EuroFlu - Weekly Electronic Bulletin - Week 12 : 21/03/2011-27/03/2011 - 01 April 2011, Issue N? 396 (Extract, edited): overall 4.4% of Pandemic H1N1 (2009) viruses resistant to oseltamivir

EuroFlu - Weekly Electronic Bulletin - Week 12 : 21/03/2011-27/03/2011 - 01 April 2011, Issue N? 396 (Extract, edited)


[Source: EuroFlu, full page: <cite cite="http://www.euroflu.org/cgi-files/bulletin_v2.cgi">EuroFlu - Bulletin Review</cite>. Extract, edited.]

EuroFlu - Weekly Electronic Bulletin - Week 12 : 21/03/2011-27/03/2011 - 01 April 2011, Issue N? 396

Low influenza activity reported in most countries of the WHO European Region

• This issue is based on data reported in week 12/2011 by 46 Member States in the WHO European Region.
• Consultation rates for influenza-like illness (ILI) and acute respiratory infection (ARI) activity continue to decrease throughout the Region and are below baseline or at pre-season levels in 29 countries.
• Sentinel hospital surveillance for severe acute respiratory infection (SARI) from 9 countries suggests that SARI hospitalizations are declining from previous peaks.
• 22% of sentinel specimens from patients with ILI or ARI, and 25% of specimens from sentinel SARI patients tested positive for influenza.
• Data from sentinel sites show that pandemic influenza A(H1N1) 2009 and influenza B continue to co-circulate in the Region, but with an increasing proportion of influenza B detections.

Current situation - week 12/2011

During week 12/2011, low influenza activity was reported in 34 out of 42 countries, a higher proportion compared to the previous week, while 8 reported medium intensity. ILI or ARI consultation rates were decreasing in all 39 countries reporting clinical data, and were either below baseline or at pre-season levels in 29 of these.

Among 43 countries reporting on the geographical spread of influenza, most reported no or sporadic activity (28 countries). Local spread was reported in 6 countries, while 7 reported regional activity, and 2 widespread.

The impact of influenza on health care systems was low in 20 and moderate in 4 of the 24 countries reporting on this indicator.

Data from sentinel hospital-based surveillance for SARI were reported from 9 countries: Armenia, Georgia, Kazakhstan, Malta, the Republic of Moldova, Romania, the Russian Federation, Serbia and Ukraine. In Kazakhstan and the Russian Federation, sentinel SARI hospitalizations continue to decrease and are now at pre-season levels. While the number of SARI hospitalizations in Armenia, Georgia, the Republic of Moldova and Serbia remained relatively unchanged compared to previous weeks, declining trends in cases have been observed in Romania and Ukraine along with decreasing percentages of SARI specimens testing positive for influenza.

Further information on the sentinel SARI surveillance systems represented in the EuroFlu bulletin can be found in the ?Overview of sentinel SARI systems in EuroFlu?.


Virological situation - week 12/2011

Pandemic influenza A(H1N1) 2009 was reported to be dominant in 4 countries and co-dominant with influenza B in 8 countries. Influenza B was dominant in 7 countries.

Sentinel physicians collected 681 respiratory specimens, of which 147 (22%) were positive for influenza virus: 50 (34%) were influenza A and 97 (66%) were influenza B. Of the influenza A viruses, 42 were subtyped: 41 (98%) as pandemic A(H1) and 1 (2%) as A(H3).

In the 13 countries testing 20 or more sentinel specimens, influenza positivity ranged from 5% to 46%, with a median of 14% (mean: 20%).

In addition, 988 non-sentinel specimens were reported positive for influenza: 595 (60%) influenza A and 393 (40%) influenza B. Of the influenza A viruses, 532 were subtyped: 516 (97%) as pandemic A(H1) and 16 (3%) as A(H3).

Sentinel hospitals participating in SARI surveillance (9 countries) collected 171 respiratory specimens, of which 42 (25%) were positive for influenza compared to 40% in the previous week. Among the 5 countries testing 10 or more sentinel SARI specimens, the percentage testing positive for influenza ranged from 0% in Malta to 43% in Ukraine (median: 23%, mean:18%).


Cumulative virological update - weeks 40/2010 - 12/2011

A total of 81 244 influenza virus detections were reported during this period, of which 57 885 (71%) were influenza A and 23 359 (29%) were influenza B.

Of the influenza A viruses, 46 119 were subtyped: 44 467 (96%) as pandemic A(H1), 1651 (4%) as influenza A(H3) and 1 as influenza A(H1).

From week 40/2010 to week 12/2011, 1470 out of 5170 sentinel SARI specimens (28%) tested positive for influenza.

Of these influenza viruses, 821 (56%) were influenza A and 649 (44%) influenza B.

Of the influenza A viruses, 569 were subtyped: 518 (91%) as pandemic A(H1) and 51 (9%) as influenza A(H3).

Since week 40/2010, 3950 influenza viruses have been characterized antigenically:

• 1952 were A(H1) pandemic A/California/7/2009 (H1N1)-like;
• 1736 were B/Brisbane/60/2008-like (B/Victoria/2/87 lineage);
• 117 were A(H3) A/Perth/16/2009 (H3N2)-like;
• 144 were B/Florida/4/2006-like (B/Yamagata/16/88 lineage), and
• 1 was B/Bangladesh/3333/2007-like (B/Yamagata/16/88 lineage).

Based on the genetic characterization of 359 influenza viruses:

• 77 belonged to the pandemic A/California/7/2009 A(H1N1) clade;
• 10 belonged to the pandemic A/Christchurch/16/2010 A(H1) clade;
• 46 belonged to the pandemic A/Hong Kong/2213/2010 A(H1) clade;
• 81 belonged to the recently emerged A/England/142/2010 subgroup characterized by S185T substitution in the HA;
• 11 belonged to the A(H3) clade represented by A/Perth/16/2009;
• 4 belonged to the A(H3) clade represented by A/Victoria/208/2009;
• 18 belonged to the subgroup represented by A/Hong Kong/2121/2010 in the A/Victoria/208/2009 A(H3) clade;
• 19 belonged to the B/Bangladesh/3333/2007 clade (Yamagata lineage), and
• 93 to the B/Brisbane/60/2008 clade (Victoria lineage).

Since week 40/2010, 9 countries (Denmark, Germany, Ireland, Italy, Netherlands, Norway, Spain, Switzerland and the United Kingdom) have screened 2399 viruses for susceptibility to the neuraminidase inhibitors oseltamivir and zanamivir. The United Kingdom analysed most of the viruses screened (1672).

Out of the 2067 pandemic A(H1N1) 2009 viruses that were tested, 1976 were sensitive to both inhibitors and 91 viruses (4.4%) carried the NA H275Y mutation.

These 91 viruses were resistant to oseltamivir but remained sensitive to zanamivir.

4 influenza A(H3N2) viruses were tested and found to be sensitive to both inhibitors.

All of the 332 influenza B viruses tested for susceptibility to oseltamivir and the 322 tested for susceptibility to zanamivir were found to be sensitive.

All 178 pandemic influenza A(H1N1) 2009 viruses and 2 A(H3N2) viruses that were screened for susceptibility to adamantanes were found to be resistant.


Comment

Clinical ILI and ARI consultation rates are below baseline or at pre-season levels in many countries of the WHO European Region and most are reporting low influenza activity. This is consistent with declines in the percentage of ILI and ARI sentinel specimens testing positive for influenza, from 33% in week 11 to 22% this week. Data from hospital-based sentinel surveillance in 9 countries suggest that SARI hospitalizations, and the percentage of SARI cases that are caused by influenza, are declining overall.

Pandemic influenza A(H1N1) 2009 and influenza B are still co-dominating in the Region, but the ratio of influenza B to influenza A is increasing.


Further information

The EuroFlu bulletin describes and comments on influenza activity in the 53 countries in the WHO European Region. For an update on the influenza situation and WHO/Europe recommendations, see the WHO/Europe web site.

Further information can be obtained from the web sites of WHO/Europe, WHO headquarters and the European Centre for Disease Prevention and Control.

Further information on severe cases associated with influenza virus infections in the European Region can be found in the ECDC Weekly Influenza Surveillance Overview.

(...)


Network comments (where available)

• Georgia
  • Increased number of SARI cases this week is caused by nosocomial spread and does not reflect situation within the country.
• Malta
  • situation stable
• Serbia
  • Sentinel SARI surveillance system in SERBIA:
  • In week 12/2011, 20 SARI from all causes were reported.
  • Out of 16 SARI specimens collected in the week 12/2011, 7 (43,8%) tested positive: 3 were influenza A and 4 were influenza B.
• Spain
  • In Spain information concerning severe illness due to influenza infection with associated admission to hospitals comes from a surveillance system developed during the 2009/2010 pandemic season specifically for this purpose.
  • Since week 40/2010 and up to week 12/2011 1360 severe hospitalised confirmed influenza cases have been reported.
  • Severely affected cases were mostly in the 15-64 year age groups (67%) and 15% were less than five years old and 18% were more than 64 years old.
  • 26% of them with no known risk factors.
  • Of 1354 cases with outcome information 154 died (13% with no known risk factors).
  • Of the severe cases 885 had information available on the status of influenza vaccination for the 2010/2011 season and only 132 (15%) cases had been immunised.
  • Monovalent pandemic vaccines 2009 were reported to have been received for 9% of hospitalised cases.
  • Most of severe and fatal cases included in the groups which were recommended influenza vaccination had not been vaccinated this season

(...)
-
------

[Giuseppe]

Weekly influenza surveillance overview, April 1, 2011 - Week 12 (edited)

Weekly influenza surveillance overview, April 1, 2011 - Week 12 (edited)


[Source: European Centre for Disease Prevention and Control (ECDC), full page: <cite cite="http://www.ecdc.europa.eu/en/publications/Publications/Forms/ECDC_DispForm.aspx?ID=663">Publications - 110401_SUR_Weekly_Influenza_Surveillance_Overview. pdf...</cite>. Edited.]

Weekly influenza surveillance overview, April 1, 2011 - Week 12

Surveillance reports - 01 Apr 2011

Available as PDF in the following languages: (English)

This document is free of charge.


ABSTRACT

The weekly/bi-weekly influenza surveillance overview is a collection of timely and relevant information regarding influenza activity in Europe. It provides key statistical data on a variety of issues including the following: sentinel surveillance of influenza like illness (ILI) and acute respiratory illness (ARI); virological surveillance; aggregate numbers of pandemic H1N1 2009; hospital surveillance of severe acute respiratory infection (SARI); mortality surveillance; and qualitative reporting. An up-to-date report is available on Fridays.

-
------

[JimO]

Re: EuroFlu - Weekly Electronic Bulletin - Week 12 : 21/03/2011-27/03/2011 - 01 April 2011, Issue N? 396 (Extract, edited): overall 4.4% of Pandemic H1N1 (2009) viruses resistant to oseltamivir

Now the majority of pH1N1 samples no longer match A/California/7/2009 A(H1N1) and there are more from the A/England/142/2010 subclade than from the A/California/7/2009 clade. I would expect to see a similar divergence in the U.S., which would likely explain why severe cases and deaths have occurred in some states where pH1N1 is circulating and not in others.

This should be sufficient evidence to stop public health officials in the U.S. from stating that the specimens collected are a good match to the vaccine. No U.S. sequences have been released from samples collected in 2011 to back up this statement.

[B] Based on the genetic characterization of 359 influenza viruses:

• 77 belonged to the pandemic A/California/7/2009 A(H1N1) clade;
• 10 belonged to the pandemic A/Christchurch/16/2010 A(H1) clade;
• 46 belonged to the pandemic A/Hong Kong/2213/2010 A(H1) clade;
• 81 belonged to the recently emerged A/England/142/2010 subgroup characterized by S185T substitution in the HA;
• 11 belonged to the A(H3) clade represented by A/Perth/16/2009;
• 4 belonged to the A(H3) clade represented by A/Victoria/208/2009;
• 18 belonged to the subgroup represented by A/Hong Kong/2121/2010 in the A/Victoria/208/2009 A(H3) clade;
• 19 belonged to the B/Bangladesh/3333/2007 clade (Yamagata lineage), and
• 93 to the B/Brisbane/60/2008 clade (Victoria lineage).

[Giuseppe]

EuroFlu - Weekly Electronic Bulletin - Week 13 : 28/03/2011-03/04/2011 - 08 April 2011, Issue N? 397 (Extract, edited)

EuroFlu - Weekly Electronic Bulletin - Week 13 : 28/03/2011-03/04/2011 - 08 April 2011, Issue N? 397 (Extract, edited)


[Source: EuroFlu, full page: <cite cite="http://www.euroflu.org/cgi-files/bulletin_v2.cgi">EuroFlu - Bulletin Review</cite>. Extract, edited.]

EuroFlu - Weekly Electronic Bulletin - Week 13 : 28/03/2011-03/04/2011 - 08 April 2011, Issue N? 397

Influenza activity continuing to decline in the WHO European Region

• This issue is based on data reported in week 13/2011 by 47 Member States in the WHO European Region.
• Clinical consultation rates for influenza-like illness (ILI) and/or acute respiratory infections (ARI) continue to decline in 35 countries, and are lower than previously observed peaks in 38 countries.
• Sentinel surveillance for hospitalised severe acute respiratory infections (SARI) in10 countries suggests that SARI hospitalizations have also passed previous peaks in each of these countries.
• 18% of sentinel specimens from patients with ILI or ARI, and 15% of specimens from sentinel SARI patients tested positive for influenza, a decline from recent weeks.
• Influenza B now represents a large majority of influenza detections from sentinel sites in the Region.

Current situation ? week 13/2011

Of the 42 countries reporting on the intensity of respiratory disease activity, 38 reported a low intensity and 5 reported a medium intensity.

Of 43 countries reporting on the geographical spread of influenza, 31 reported none or sporadic activity. Local activity was reported in 6 countries, while 5 reported regional activity, and 1 (Croatia) reported widespread activity.

The impact of influenza on health care systems was reported to be low in 22 and moderate in 2 of the 24 countries reporting on this indicator.

Trends in clinical and virological data suggest declining influenza activity in the Region.

Clinical consultation rates for influenza-like illness (ILI) and/or acute respiratory infection (ARI) activity continue to decline in 35 countries, and are lower than previously observed peaks in 38 countries. In addition, of the 17 countries indicating a baseline threshold for influenza activity, all reported ILI or ARI clinical consultation rates to be below the seasonal threshold.

Declining trends in influenza positivity rates can also be observed in 16 of the 18 countries that have reported consistently on this indicator.

Data from sentinel hospital-based surveillance for SARI were reported from 10 countries: Albania, Armenia, Georgia, Kazakhstan, Romania, the Republic of Moldova, the Russian Federation, Serbia and Ukraine. Sentinel SARI hospitalizations have declined to levels below previous peaks in all of these countries. This has been accompanied by concurrent declines in the percent of sentinel SARI specimens testing positive for influenza. There has also been a decrease in the relative percentage of sentinel SARI hospitalisations in persons over age four years.

Although Kyrgyzstan reported an increase in sentinel SARI hospitalizations during the current week, no sentinel specimens from these patients were reported to be positive for influenza, and this increase was mostly the result of recent hospitalisations in the 0-4 age group.

Further information on the sentinel SARI surveillance systems represented in the EuroFlu bulletin can be found in the ?Overview of sentinel SARI systems in EuroFlu?.


Virological situation - week 13/2011

Pandemic influenza A(H1N1) 2009 was reported to be dominant in 2 countries and co-dominant with influenza B in 3 countries. Influenza B was reported to be dominant in 10 countries.

Sentinel physicians collected 590 respiratory specimens, of which 106 (18%) were positive for influenza virus: 18 (17%) were influenza A and 88 (83%) were influenza B. Of the influenza A viruses, 15 were subtyped: 15 (100%) as pandemic A(H1).

In the 12 countries testing 20 or more sentinel specimens, influenza positivity ranged from 0% to 50%, with a median of 11% (mean: 20%).

In addition, 587 non-sentinel specimens were reported positive for influenza: 315 (54%) influenza A and 272 (46%) influenza B. Of the influenza A viruses, 261 were subtyped: 247 (95%) as pandemic A(H1) and 14 (5%) as A(H3).

Sentinel hospitals participating in SARI surveillance (10 countries) collected 113 sentinel SARI specimens of which 17 (15%) were positive for influenza (compared to 25% positive in week 12/2011). Among the 5 countries testing 10 or more sentinel SARI specimens, the percentage testing positive for influenza ranged from 0% in Kyrgyzstan to 30% in Georgia (median: 8%, mean:13%).


Cumulative virological update - weeks 40/2010 - 13/2011

A total of 82 150 influenza virus detections were reported during this period, of which 58 399 (71%) were influenza A and 23 751 (29%) were influenza B.

Of the influenza A viruses, 46 551 were subtyped: 44 879 (96%) as pandemic A(H1), 1671 (4%) as influenza A(H3) and 1 as influenza A(H1).

From week 40/2010 through week 13/2011, 1521 out of 5343 sentinel SARI specimens (28%) tested positive for influenza.

Of these influenza viruses, 863 (57%) were influenza A and 658 (43%) influenza B.

Of the influenza A viruses, 684 were subtyped: 632 (92%) as pandemic A(H1) and 52 (8%) as influenza A(H3).

Since week 40/2010, 4443 influenza viruses have been characterized antigenically:

• 2262 were A(H1) pandemic A/California/7/2009 (H1N1)-like;
• 1865 were B/Brisbane/60/2008-like (B/Victoria/2/87 lineage);
• 150 were A(H3) A/Perth/16/2009 (H3N2)-like;
• 164 were B/Florida/4/2006-like (B/Yamagata/16/88 lineage), and
• 2 were B/Bangladesh/3333/2007-like (B/Yamagata/16/88 lineage).

Based on the genetic characterization of 550 influenza viruses:

• 160 belonged to the pandemic A/California/7/2009 A(H1N1) clade;
• 10 belonged to the pandemic A/Christchurch/16/2010 A(H1) clade;
• 46 belonged to the pandemic A/Hong Kong/2213/2010 A(H1) clade;
• 124 belonged to the recently emerged A/England/142/2010 subgroup characterized by S185T substitution in the HA;
• 12 belonged to the A(H3) clade represented by A/Perth/16/2009;
• 7 belonged to the A(H3) clade represented by A/Victoria/208/2009;
• 30 belonged to the subgroup represented by A/Hong Kong/2121/2010 in the A/Victoria/208/2009 A(H3) clade;
• 19 belonged to the B/Bangladesh/3333/2007 clade (Yamagata lineage), and
• 142 to the B/Brisbane/60/2008 clade (Victoria lineage).

Since week 40/2010, 9 countries (Denmark, Germany, Ireland, Italy, Netherlands, Norway, Spain, Switzerland and the United Kingdom) have screened 2407 viruses for susceptibility to the neuraminidase inhibitors oseltamivir and zanamivir. The United Kingdom analysed most of the viruses screened (1672). Out of the 2069 pandemic A(H1N1) 2009 viruses that were tested, 1978 were sensitive to both inhibitors and 91 viruses (4.4%) carried the NA H275Y mutation. These 91 viruses were resistant to oseltamivir but remained sensitive to zanamivir. 4 influenza A(H3N2) viruses were tested and found to be sensitive to both inhibitors. All of the 338 influenza B viruses tested for susceptibility to oseltamivir and the 328 tested for susceptibility to zanamivir were found to be sensitive.

All 178 pandemic influenza A(H1N1) 2009 viruses and 2 A(H3N2) viruses that were screened for susceptibility to adamantanes were found to be resistant.


Comment

Trends in clinical and virological data suggest that influenza activity is substantially declining across the WHO European Region. Recent declines in clinical indicators have been observed in nearly all countries, and many are below seasonal thresholds for influenza activity. The percent of sentinel ILI, ARI, and SARI specimens that have tested positive for influenza, and the circulation of pandemic influenza A(H1N1) 2009 relative to influenza B has also declined during recent weeks.


Further information

The EuroFlu bulletin describes and comments on influenza activity in the 53 countries in the WHO European Region. For an update on the influenza situation and WHO/Europe recommendations, see the WHO/Europe web site.Further information can be obtained from the web sites of WHO/Europe, WHO headquarters and the European Centre for Disease Prevention and Control.

Further information on severe cases associated with influenza virus infections in the European Region can be found in the ECDC Weekly Influenza Surveillance Ove

(...)


Network comments (where available)

• Serbia
  • Sentinel SARI surveillance system in SERBIA:
    • In week 13/2011, 13 SARI from all causes were reported.
    • Out of 8 SARI specimens collected in the week 13/2011, 3 (37,5%) tested positive: 1 was influenza A and 2 were influenza B.
• Spain
  • In Spain information concerning severe illness due to influenza infection with associated admission to hospitals comes from a surveillance system developed during the 2009/2010 pandemic season specifically for this purpose.
  • Since week 40/2010 and up to week 13/2011 1380 severe hospitalised confirmed influenza cases have been reported.
  • Severely affected cases were mostly in the 15-64 year age groups (63%) and 19% were less than five years old and 18% were more than 64 years old.
  • 26% of them with no known risk factors.
  • Of 1374 cases with outcome information 155 died (13% with no known risk factors).
  • Of the severe cases 892 had information available on the status of influenza vaccination for the 2010/2011 season and only 134 (15%) cases had been immunised.
  • Monovalent pandemic vaccines 2009 were reported to have been received for 10% of hospitalised cases.
  • Most of severe and fatal cases included in the groups which were recommended influenza vaccination had not been vaccinated this season

(...)
-
------

[Giuseppe]

EuroFlu - Weekly Electronic Bulletin - Week 14 : 04/04/2011-10/04/2011 - 15 April 2011, Issue N? 398 (extract, edited)

EuroFlu - Weekly Electronic Bulletin - Week 14 : 04/04/2011-10/04/2011 - 15 April 2011, Issue N? 398 (extract, edited)



[Source: EuroFlu, full page: (LINK). Extract, edited.]
EuroFlu - Weekly Electronic Bulletin - Week 14 : 04/04/2011-10/04/2011 - 15 April 2011, Issue N? 398

Influenza activity is returning to low levels in most parts of the WHO European Region

• This issue is based on data reported in week 14/2011 by 47 Member States in the WHO European Region.
• Clinical consultation rates for influenza-like illness (ILI) and/or acute respiratory infections (ARI) continue to decline or have returned to baseline levels in 36 countries.
• Sentinel surveillance for hospitalized severe acute respiratory infections (SARI) in 10 countries suggests that SARI hospitalizations have passed previous peaks in all of these countries.
• 13% of sentinel specimens from patients with ILI or ARI, and 3% of specimens from sentinel SARI patients tested positive for influenza.
• In week 14/2011, influenza B viruses represented the majority of influenza detections from sentinel sites in the Region.

Current situation - week 14/2011
Of the 37 countries reporting on the intensity of respiratory disease activity, 34 reported low intensity and 3 reported medium intensity.
Of 38 countries reporting on the geographical spread of influenza, 28 reported none or sporadic activity. Local activity was reported in 5 countries, while 4 reported regional activity, and 1 (Croatia) reported widespread activity.
The impact of influenza on health care systems was reported to be low in 19 and moderate in 2 of the 21 countries reporting on this indicator.
Trends in clinical and virological data indicate further declines in influenza activity in the Region.
Of the 15 countries indicating a baseline threshold for influenza activity, all reported ILI or ARI clinical consultation rates to be below these thresholds.
Data from sentinel hospital-based surveillance for SARI were reported by 10 countries: Albania, Armenia, Georgia, Kazakhstan, Kyrgyzstan, Romania, the Republic of Moldova, the Russian Federation, Serbia and Ukraine.
Sentinel SARI hospitalizations have declined to levels below previous peaks in all of these countries. This has been accompanied by concurrent declines in the percentage of sentinel SARI specimens testing positive for influenza.
Although a few countries (Armenia, Kazakhstan and Georgia) reported a slight increase in sentinel SARI hospitalizations during the current week, the percentage of specimens testing positive for influenza was very low (3%).
Further information on the sentinel SARI surveillance systems represented in the EuroFlu bulletin can be found in the ?Overview of sentinel SARI systems in EuroFlu?.

Virological situation - week 14/2011
No country reported pandemic influenza A(H1N1) 2009 virus to be dominant but it was co-dominant with influenza B virus in 6 countries. Influenza B virus was dominant in 4 countries.
Sentinel physicians collected 506 respiratory specimens, of which 64 (13%) were positive for influenza virus: 19 (30%) were influenza A and 45 (70%) were influenza B.
Of the influenza A viruses, 12 were subtyped: 9 (75%) as pandemic A(H1) and 3 (25%) as A(H3).
In the 8 countries testing 20 or more sentinel specimens, influenza positivity ranged from 0% to 46%, with a median of 11% (mean: 15%).
In addition, 386 non-sentinel specimens were reported positive for influenza: 204 (53%) influenza A and 182 (47%) influenza B.
Of the influenza A viruses, 154 were subtyped: 123 (80%) as pandemic A(H1) and 31 (20%) as A(H3).
Sentinel hospitals participating in SARI surveillance (10 countries) collected 111 sentinel SARI specimens of which 3 (3%) were positive for influenza (compared to 15% positive in week 13/2011). Among the 3 countries testing 10 or more sentinel SARI specimens, the percentage testing positive for influenza ranged from 0% in Georgia and the Russian Federation to 4% in Kazakhstan.

Cumulative virological update - weeks 40/2010 - 14/2011
A total of 82 759 influenza virus detections were reported during this period, of which 58 749 (71%) were influenza A and 24 010 (29%) were influenza B.
Of the influenza A viruses, 46 843 were subtyped: 45 115 (96%) as pandemic A(H1), 1727 (4%) as influenza A(H3) and 1 as influenza A(H1).
From week 40/2010 through week 14/2011, 1526 out of 5471 sentinel SARI specimens (28%) tested positive for influenza.
Of these influenza viruses, 867 (57%) were influenza A and 659 (43%) influenza B.
Of the influenza A viruses, 688 were subtyped: 636 (92%) as pandemic A(H1) and 52 (8%) as influenza A(H3).
Since week 40/2010, 4654 influenza viruses have been characterized antigenically:

• 2387 were A(H1) pandemic A/California/7/2009 (H1N1)-like;
• 1936 were B/Brisbane/60/2008-like (B/Victoria/2/87 lineage);
• 155 were A(H3) A/Perth/16/2009 (H3N2)-like;
• 174 were B/Florida/4/2006-like (B/Yamagata/16/88 lineage), and
• 2 were B/Bangladesh/3333/2007-like (B/Yamagata/16/88 lineage).

Based on the genetic characterization of 566 influenza viruses:

• 150 belonged to the pandemic A/California/7/2009 A(H1N1) clade;
• 10 belonged to the pandemic A/Christchurch/16/2010 A(H1) clade;
• 46 belonged to the pandemic A/Hong Kong/2213/2010 A(H1) clade;
• 132 belonged to the recently emerged A/England/142/2010 subgroup characterized by S185T substitution in the HA;
• 12 belonged to the A(H3) clade represented by A/Perth/16/2009;
• 6 belonged to the A(H3) clade represented by A/Victoria/208/2009;
• 28 belonged to the subgroup represented by A/Hong Kong/2121/2010 in the A/Victoria/208/2009 A(H3) clade;
• 20 belonged to the B/Bangladesh/3333/2007 clade (Yamagata lineage), and
• 162 to the B/Brisbane/60/2008 clade (Victoria lineage).

Since week 40/2010, 9 countries (Denmark, Germany, Ireland, Italy, Netherlands, Norway, Spain, Switzerland and the United Kingdom) have screened 3532 viruses for susceptibility to the neuraminidase inhibitors oseltamivir and zanamivir.
The United Kingdom analysed most of the viruses screened (1672).
Of the 3182 pandemic A(H1N1) 2009 viruses that were tested, 3090 were sensitive to both inhibitors and 92 viruses (2.9%) carried the NA H275Y mutation.
These 92 viruses were resistant to oseltamivir but remained sensitive to zanamivir.
Four influenza A(H3N2) viruses were tested and found to be sensitive to both inhibitors.
All of the 346 influenza B viruses tested for susceptibility to oseltamivir and the 340 tested for susceptibility to zanamivir were found to be sensitive.
All 197 pandemic influenza A(H1N1) 2009 viruses and 10 A(H3N2) viruses that were screened for susceptibility to adamantanes were found to be resistant.

Comment
Trends in clinical and virological data suggest that influenza activity is declining further across the WHO European Region. Recent declines in clinical indicators have been observed in nearly all countries, and many are below baseline thresholds for influenza activity. Influenza B now dominates in circulation relative to pandemic influenza A(H1N1) 2009, but positivity rates continue to decline for all influenza types and sub-types of influenza.

Further information
The EuroFlu bulletin describes and comments on influenza activity in the 53 countries in the WHO European Region. For an update on the influenza situation and WHO/Europe recommendations, see the WHO/Europe web site. Further information can be obtained from the web sites of WHO/Europe, WHO headquarters and the European Centre for Disease Prevention and Control. Further information on severe cases associated with influenza virus infections in the European Region can be found in the ECDC Weekly Influenza Surveillance Overview.

Erratum
The geographical spread reported by Wales in week 14/2011 is incorrect. The geographical spread should be 'no activity'.
(?)

Network comments (where available)

• Serbia
  • Sentinel SARI surveillance system in SERBIA:
    • In week 14/2011, 6 SARI from all causes were reported.
    • Out of 3 SARI specimens collected in the week 14/2011, 1 (33,3%) tested positive: 1 was influenza B.
• Spain
  • In Spain information concerning severe illness due to influenza infection with associated admission to hospitals comes from a surveillance system developed during the 2009/2010 pandemic season specifically for this purpose.
  • Since week 40/2010 and up to week 14/2011 1386 severe hospitalised confirmed influenza cases have been reported.
  • Severely affected cases were mostly in the 15-64 year age groups (63%) and 15% were less than five years old and 18% were more than 64 years old.
  • 25% of them with no known risk factors.
  • Of 1382 cases with outcome information 156 died (13% with no known risk factors).
  • Of the severe cases 893 had information available on the status of influenza vaccination for the 2010/2011 season and only 134 (15%) cases had been immunised.
  • Monovalent pandemic vaccines 2009 were reported to have been received for 10% of hospitalised cases.
  • Most of severe and fatal cases included in the groups which were recommended influenza vaccination had not been vaccinated this season

(?)
-
-------

[Giuseppe]

EuroFlu - Weekly Electronic Bulletin - Week 15 : 11/04/2011-17/04/2011 - 20 April 2011, Issue N? 399 (April 22 2011, edited)

[Source: EuroFlu, full page: (LINK). Extract, edited.]

EuroFlu - Weekly Electronic Bulletin - Week 15 : 11/04/2011-17/04/2011 - 20 April 2011, Issue N? 399



Sporadic influenza activity in the WHO European Region

This issue is based on data reported in week 15/2011 by 35 Member States in the WHO European Region.
Consultation rates for influenza-like illness (ILI) and acute respiratory infection (ARI) activity are below baseline or at pre-season levels in most countries.
Hospitalizations for severe acute respiratory infection (SARI) are declining overall in countries with sentinel hospital-based surveillance for SARI.
10% of sentinel specimens from patients with ILI or ARI, and 4% of specimens from sentinel SARI patients, tested positive for influenza.
Influenza B continues to make up most of the influenza detections from sentinel sites in the Region this week.

Current situation ? week 15/2011

During week 15/2011, low influenza activity was reported in 22 countries and 2 reported medium intensity. ILI or ARI consultation rates have returned to pre-season levels or are below the national baselines in all of the 21 countries reporting clinical data this week.

Among the 25 countries reporting on the geographical spread of influenza, most reported no or sporadic activity (21 countries).

Local spread was reported in 2 countries (Armenia and Croatia), while 2 reported regional spread (Georgia and Lithuania). The impact of influenza on health care systems was low in all but one (Armenia) of the 17 countries reporting on this indicator.

Data on sentinel hospital-based surveillance for SARI were reported from 8 countries: Armenia, Georgia, Kazakhstan, the Republic of Moldova, Romania, the Russian Federation, Serbia and Ukraine. SARI hospitalizations are declining overall and appear to have reached pre-season levels in Kazakhstan, Romania and Serbia. Further information on the sentinel SARI surveillance systems represented in the EuroFlu bulletin can be found in the ?Overview of sentinel SARI systems in EuroFlu?.



Virological situation ? week 15/2011

Ukraine reported pandemic influenza A(H1N1) 2009 virus to be dominant, and it was co-dominant with influenza B virus in 3 countries. Influenza B virus was reported as the dominant type in 5 countries.

Sentinel physicians collected 310 respiratory specimens, of which 31 (10%) were positive for influenza virus: 5 (16%) were influenza A and 26 (84%) were influenza B. All influenza A viruses were subtyped: 2 as pandemic A(H1) and 3 as A(H3). In the 6 countries testing 20 or more sentinel specimens, influenza positivity ranged from 5% to 18%, with a median of 8% (mean: 9%).

In addition, 203 non-sentinel specimens were reported positive for influenza: 104 (51%) influenza A and 99 (49%) influenza B. Of the influenza A viruses, 81 were subtyped: 71 (88%) as pandemic A(H1) and 10 (12%) as A(H3).

Sentinel hospitals representing 8 of 10 countries participating in SARI surveillance collected 112 SARI specimens, of which 4 (4%) were positive for influenza. Among the 3 countries testing 10 or more sentinel SARI specimens, the percentage testing positive for influenza ranged from 0% in Ukraine to 5% in the Russian Federation.



Cumulative virological update - weeks 40/2010 - 15/2011

A total of 83 042 influenza virus detections were reported during this period, of which 58 911 (71%) were influenza A and 24 131 (29%) were influenza B. Of the influenza A viruses, 46 957 were subtyped: 45 211 (96%) as pandemic A(H1) and 1746 (4%) as A(H3).

From week 40/2010 through week 15/2011, 1531 out of 5484 sentinel SARI specimens (28%) tested positive for influenza. Of these influenza viruses, 871 (57%) were influenza A and 660 (43%) influenza B. Of the influenza A viruses, 691 were subtyped: 638 (92%) as pandemic A(H1) and 53 (8%) as influenza A(H3).

Since week 40/2010, 4728 influenza viruses have been characterized antigenically:

• 2427 were A(H1) pandemic A/California/7/2009 (H1N1)-like;
• 1963 were B/Brisbane/60/2008-like (B/Victoria/2/87 lineage);
• 155 were A(H3) A/Perth/16/2009 (H3N2)-like;
• 181 were B/Florida/4/2006-like (B/Yamagata/16/88 lineage), and
• 2 were B/Bangladesh/3333/2007-like (B/Yamagata/16/88 lineage).

Based on the genetic characterization of 565 influenza viruses:

• 150 belonged to the pandemic A/California/7/2009 A(H1N1) clade;
• 10 belonged to the pandemic A/Christchurch/16/2010 A(H1) clade;
• 46 belonged to the pandemic A/Hong Kong/2213/2010 A(H1) clade;
• 130 belonged to the recently emerged A/England/142/2010 subgroup characterized by S185T substitution in the HA;
• 12 belonged to the A(H3) clade represented by A/Perth/16/2009;
• 5 belonged to the A(H3) clade represented by A/Victoria/208/2009;
• 29 belonged to the subgroup represented by A/Hong Kong/2121/2010 in the A/Victoria/208/2009 A(H3) clade;
• 20 belonged to the B/Bangladesh/3333/2007 clade (Yamagata lineage), and
• 163 to the B/Brisbane/60/2008 clade (Victoria lineage).

Since week 40/2010, 9 countries (Denmark, Germany, Ireland, Italy, Netherlands, Norway, Spain, Switzerland and the United Kingdom) have screened 3533 viruses for susceptibility to the neuraminidase inhibitors oseltamivir and zanamivir.

The United Kingdom analysed most of the viruses screened (1672).

Of the 3183 pandemic A(H1N1) 2009 viruses that were tested, 3091 were sensitive to both inhibitors and 92 viruses (3%) carried the NA H275Y mutation.

These 92 viruses were resistant to oseltamivir but remained sensitive to zanamivir.

Four influenza A(H3N2) viruses were tested and found to be sensitive to both inhibitors.

All of the 346 influenza B viruses tested for susceptibility to oseltamivir and the 340 tested for susceptibility to zanamivir were found to be sensitive.

All 197 pandemic influenza A(H1N1) 2009 viruses and 10 A(H3N2) viruses that were screened for susceptibility to adamantanes were found to be resistant.



Comment

Influenza activity has returned to pre-season levels in most countries across the WHO European Region, along with a continued decrease in the percentage of ILI and ARI sentinel specimens testing positive for influenza. Influenza B accounted for 84% of the total positive specimens collected this week, although the majority of virus detections since the start of the season have been pandemic influenza A(H1N1) 2009. Countries with hospital-based sentinel surveillance continue to report SARI hospitalizations, although numbers are declining overall, along with a decreasing proportion of samples testing positive for influenza.



Further information

The EuroFlu bulletin describes and comments on influenza activity in the 53 countries in the WHO European Region. For an update on the influenza situation and WHO/Europe recommendations, see the WHO/Europe web site.

Further information can be obtained from the web sites of WHO/Europe, WHO headquarters and the European Centre for Disease Prevention and Control.

Further information on severe cases associated with influenza virus infections in the European Region can be found in the ECDC Weekly Influenza Surveillance Overview.


(?)


Network comments (where available)

Serbia
Sentinel SARI surveillance system in SERBIA: In week 15/2011, 2 SARI from all causes were reported. Out of 2 SARI specimens collected in the week 15/2011, no one was positive.

(?)

-
------

[gsgs]

Re: EuroFlu - Weekly Electronic Bulletin - Week 15 : 11/04/2011-17/04/2011 - 20 April 2011, Issue N? 399 (April 22 2011, edited)

highest in Azerbaijan

http://www.euroflu.org/cgi-files/figures2002.cgi?year=2011&week=15&region=Azerbaijan&type=c

[Giuseppe]

EuroFlu - Weekly Electronic Bulletin - Week 16 : 18/04/2011-24/04/2011 - 29 April 2011, Issue N? 400 (edited)

[Source: EuroFlu, full page: (LINK). Extract, edited.]

EuroFlu - Weekly Electronic Bulletin - Week 16 : 18/04/2011-24/04/2011 - 29 April 2011, Issue N? 400



Influenza activity has returned to ?out of season? levels in most countries of the WHO European Region

This issue is based on data reported in week 16/2011 by 45 Member States in the WHO European Region.
Consultation rates for influenza-like illness (ILI) and acute respiratory infection (ARI) activity are below baseline thresholds or at pre-season levels in most countries.
Hospitalizations for severe acute respiratory infection (SARI) continue to decline in most countries with sentinel hospital-based surveillance for SARI.
5% of sentinel specimens from patients with ILI or ARI, and 3% of specimens from sentinel SARI patients, tested positive for influenza.

Current situation ? week 16/2011

During week 16/2011, 35 countries reported low intensity of respiratory-disease activity and 2 (Armenia and the Russian Federation), medium intensity. ILI or ARI consultation rates have returned to pre-season levels or are below the national baseline thresholds in all but 1 (Azerbaijan) of the 36 countries reporting epidemiological data this week.

Among the 37 countries reporting on the geographical spread of influenza, 35 reported no or sporadic activity. Armenia reported local spread, and Georgia, regional spread. The impact of influenza on health care systems was low in all but 1 (Armenia) of the 20 countries reporting on this indicator.

Data on sentinel hospital-based surveillance for SARI were reported in 10 countries: Armenia, Georgia, Kazakhstan, Kyrgyzstan, Malta, the Republic of Moldova, Romania, the Russian Federation, Serbia and Ukraine. SARI hospitalizations are declining overall and are back to pre-season levels in Kazakhstan, Romania, Serbia and Ukraine.

In Georgia, SARI hospitalizations have increased over the last three weeks; this is driven by increases in hospitalizations in the group aged 0?4, however, and no sentinel SARI specimens tested positive for influenza in the country during week 16.
Further information on the sentinel SARI surveillance systems represented in the EuroFlu bulletin can be found in the ?Overview of sentinel SARI systems in EuroFlu?.



Virological situation ? week 16/2011

Influenza B virus was dominant in three countries, and co-dominant with pandemic influenza A(H1N1) 2009 in two others. Ukraine reported pandemic influenza A(H1N1) 2009 virus to be dominant.

Sentinel physicians collected 162 respiratory specimens, of which 8 (5%) were positive for influenza virus: 3 (38%) were influenza A and 5 (62%) were influenza B. Two of the three influenza A viruses were subtyped: both were pandemic A(H1).

In the 2 countries testing 20 or more sentinel specimens, influenza positivity ranged from 3% to 5%.

In addition, 140 non-sentinel specimens were reported positive for influenza: 63 (45%) influenza A and 77 (55%) influenza B. Of the influenza A viruses, 54 were subtyped: 51 (94%) as pandemic A(H1) and 3 (6%) as A(H3).

Sentinel hospitals participating in SARI surveillance in 10 countries collected 64 specimens from SARI patients of which 2 (3%) were positive for influenza.



Cumulative virological update ? weeks 40/2010 ? 16/2011

A total of 77 462 influenza virus detections was reported during this period, of which 54 949 (71%) were influenza A and 22 513 (29%) were influenza B. Of the influenza A viruses, 46 281 were subtyped: 44 542 (96%) as pandemic A(H1) and 1739 (4%) as A(H3).

From week 40/2010 through week 16/2011, 1533 out of 5525 sentinel SARI specimens (28%) tested positive for influenza: 872 (57%) were influenza A and 661 (43%) influenza B. Of the influenza A viruses, 691 were subtyped: 638 (92%) as pandemic A(H1) and 53 (8%) as influenza A(H3).

Since week 40/2010, 4515 influenza viruses have been characterized antigenically:

• 2329 were A(H1) pandemic A/California/7/2009 (H1N1)-like;
• 1860 were B/Brisbane/60/2008-like (B/Victoria/2/87 lineage);
• 151 were A(H3) A/Perth/16/2009 (H3N2)-like;
• 173 were B/Florida/4/2006-like (B/Yamagata/16/88 lineage), and
• 2 were B/Bangladesh/3333/2007-like (B/Yamagata/16/88 lineage).

Based on the genetic characterization of 585 influenza viruses:

• 166 belonged to the pandemic A/California/7/2009 A(H1N1) clade;
• 10 belonged to the pandemic A/Christchurch/16/2010 A(H1) clade;
• 46 belonged to the pandemic A/Hong Kong/2213/2010 A(H1) clade;
• 136 belonged to the recently emerged A/England/142/2010 subgroup characterized by S185T substitution in the HA;
• 12 belonged to the A(H3) clade represented by A/Perth/16/2009;
• 5 belonged to the A(H3) clade represented by A/Victoria/208/2009;
• 29 belonged to the subgroup represented by A/Hong Kong/2121/2010 in the A/Victoria/208/2009 A(H3) clade;
• 20 belonged to the B/Bangladesh/3333/2007 clade (Yamagata lineage), and
• 161 to the B/Brisbane/60/2008 clade (Victoria lineage).

Since week 40/2010, 9 countries (Denmark, Germany, Ireland, Italy, Netherlands, Norway, Spain, Switzerland and the United Kingdom) have screened 3519 viruses for susceptibility to the neuraminidase inhibitors oseltamivir and zanamivir.
The United Kingdom analysed most of the viruses screened (1672).

Of the 3164 pandemic A(H1N1) 2009 viruses that were tested, 3072 were sensitive to both inhibitors and 92 viruses (2.9%) carried the NA H275Y mutation.

These 92 viruses were resistant to oseltamivir but remained sensitive to zanamivir.

9 influenza A(H3N2) viruses were tested and found to be sensitive to both inhibitors.

All of the 346 influenza B viruses tested for susceptibility to oseltamivir and the 340 tested for susceptibility to zanamivir were found to be sensitive.

All 197 pandemic influenza A(H1N1) 2009 viruses and 10 A(H3N2) viruses that were screened for susceptibility to adamantanes were found to be resistant.



Comment

Influenza activity has returned to pre-season levels in most countries across the WHO European Region. At present, a very low percentage (< 5%) of sentinel ILI/ARI and SARI specimens is testing positive for influenza.



Further information

The EuroFlu bulletin describes and comments on influenza activity in the 53 countries in the WHO European Region. For an update on the influenza situation and WHO/Europe recommendations, see the WHO/Europe web site.

Further information can be obtained from the web sites of WHO/Europe, WHO headquarters and the European Centre for Disease Prevention and Control (ECDC).

Further information on severe cases associated with influenza virus infections in the European Region can be found in the ECDC Weekly Influenza Surveillance Overview.

(?)

--
------

[Giuseppe]

EuroFlu - Weekly Electronic Bulletin - Week 17 : 25/04/2011-01/05/2011 - 06 May 2011, Issue N? 401 (extract, edited)

[Source: EuroFlu, full page: (LINK). Extract, edited.]

EuroFlu - Weekly Electronic Bulletin - Week 17 : 25/04/2011-01/05/2011 - 06 May 2011, Issue N? 401



Influenza season ending in the WHO European Region

This issue is based on data reported in week 17/2011 by 44 Member States in the WHO European Region.
Consultation rates for influenza-like illness (ILI) and acute respiratory infection (ARI) are now at pre-season levels in all countries.
Sentinel-hospital surveillance data for severe acute respiratory infection (SARI) from seven countries shows that SARI hospitalizations have declined to levels observed at the beginning of the season.
Less than 2% of sentinel specimens from patients with ILI or ARI, and 2% of specimens from sentinel SARI patients tested positive for influenza.

Current situation ? week 17/2011

During week 17/2011, all but one country (Armenia) reported low influenza activity.

ILI or ARI consultation rates either continued to decline further or were at very low levels in all of the 36 countries reporting clinical data this week.

Among 39 countries reporting on the geographical spread of influenza, 37 reported no or sporadic activity.

Armenia and Lithuania reported local spread, and Georgia, regional activity.

The impact of influenza on health care systems was low in 20 and moderate in 2 of the 22 countries reporting on this indicator.

Seven countries reported data from sentinel hospital-based surveillance systems for SARI: Armenia, Kazakhstan, the Republic of Moldova, Romania, the Russian Federation, Serbia and Ukraine.

SARI hospitalizations have returned to pre-season levels in these countries and, although influenza detections have been reported from sentinel sites in recent weeks, the percentage of samples testing positive is very low.

Further information on the sentinel SARI surveillance systems represented in the EuroFlu bulletin can be found in the ?Overview of sentinel SARI systems in EuroFlu?.



Virological situation ? week 17/2011

Sentinel physicians collected 136 respiratory specimens, of which only 2 (2%) were positive for influenza virus: 1 was pandemic A(H1) and 1 was influenza B.

One country, the Russian Federation, tested 20 or more sentinel specimens, and influenza was detected in 2% of the samples.

In addition, 70 non-sentinel specimens were reported positive for influenza: 37 (53%) influenza B and 33 (47%) influenza A. Of the influenza A viruses, 25 were subtyped: 21 (84%) as pandemic A(H1) and 4 (16%) as A(H3).

Sentinel hospitals participating in SARI surveillance collected 41 respiratory specimens, of which 1 (2%) was positive for influenza.

Only the Russian Federation tested more than 10 sentinel SARI specimens, finding 1 positive specimen, to yield a 3% positivity in the country.



Cumulative virological update ? weeks 40/2010 ? 17/2011

A total of 83 369 influenza virus detections were reported during this period, of which 59 075 (71%) were influenza A and 24 294 (29%) were influenza B.

Of the influenza A viruses, 47 068 were subtyped: 45 311 (96%) as pandemic A(H1) and 1757 (4%) as influenza A(H3).

From week 40/2010 to week 17/2011, 1540 out of 5622 sentinel SARI specimens (27%) tested positive for influenza.

Of these influenza viruses, 876 (57%) were influenza A and 664 (43%) influenza B.

Of the influenza A viruses, 696 were subtyped: 643 (92%) as pandemic A(H1) and 53 (8%) as influenza A(H3).

Since week 40/2010, 5250 influenza viruses have been characterized antigenically:

• 2622 were A(H1) pandemic A/California/7/2009 (H1N1)-like;
• 2255 were B/Brisbane/60/2008-like (B/Victoria/2/87 lineage);
• 197 were B/Florida/4/2006-like (B/Yamagata/16/88 lineage);
• 174 were A(H3) A/Perth/16/2009 (H3N2)-like; and
• 2 were B/Bangladesh/3333/2007-like (B/Yamagata/16/88 lineage).

Based on the genetic characterization of 607 influenza viruses:

• 169 belonged to the pandemic A/California/7/2009 A(H1N1) cluster;
• 10 belonged to the pandemic A/Christchurch/16/2010 A(H1) cluster;
• 46 belonged to the pandemic A/Hong Kong/2213/2010 A(H1) cluster;
• 142 belonged to the recently emerged A/England/142/2010 subgroup characterized by S185T substitution in the HA;
• 12 belonged to the A(H3) clade represented by A/Perth/16/2009;
• 5 belonged to the A(H3) clade represented by A/Victoria/208/2009;
• 29 belonged to the subgroup represented by A/Hong Kong/2121/2010 in the A/Victoria/208/2009 A(H3) clade;
• 23 belonged to the B/Bangladesh/3333/2007 clade (Yamagata lineage), and
• 171 to the B/Brisbane/60/2008 clade (Victoria lineage).

Since week 40/2010, nine countries (Denmark, Germany, Ireland, Italy, the Netherlands, Norway, Spain, Switzerland and the United Kingdom) had screened 3533 viruses for susceptibility to the neuraminidase inhibitors oseltamivir and zanamivir.

The United Kingdom analysed most of the viruses screened (1672).

Of the 3169 pandemic A(H1N1) 2009 viruses that were tested, 3077 were sensitive to both inhibitors and 92 viruses (2.9%) carried the NA H275Y mutation.

These 92 viruses were resistant to oseltamivir but remained sensitive to zanamivir.

18 influenza A(H3N2) viruses were tested and found to be sensitive to both inhibitors.

All of the 346 influenza B viruses tested for susceptibility to oseltamivir and the 340 tested for susceptibility to zanamivir were found to be sensitive.

All 197 pandemic influenza A(H1N1) 2009 viruses and 10 A(H3N2) viruses that were screened for susceptibility to adamantanes were found to be resistant.



Comment

ILI and ARI consultation rates are low throughout the WHO European Region. The great majority of countries is reporting no or sporadic influenza activity and the percentage of sentinel ILI, ARI, and SARI samples testing positive for influenza has declined to pre-season levels.



Further information

The EuroFlu bulletin describes and comments on influenza activity in the 53 countries in the WHO European Region. For an update on the influenza situation and WHO/Europe recommendations, see the WHO/Europe web site.

Further information can be obtained from the web sites of WHO/Europe, WHO headquarters and the European Centre for Disease Prevention and Control (ECDC).

Further information on severe cases associated with influenza virus infections in the European Region can be found in the ECDC Weekly Influenza Surveillance Overview.

(?)



Country comments (where available)

Spain

In Spain information concerning severe illness due to influenza infection with associated admission to hospitals comes from a surveillance system developed during the 2009/2010 pandemic season specifically for this purpose.

Since week 40/2010 and up to week 17/2011 1409 severe hospitalised confirmed influenza cases have been reported.
Severely affected cases were mostly in the 15-64 year age groups (63%) and 15% were less than five years old and 18% were more than 64 years old.

26% of them with no known risk factors.

Of 1407 cases with outcome information 165 died (12% with no known risk factors).

Of the severe cases 899 had information available on the status of influenza vaccination for the 2010/2011 season and only 136 (15%) cases had been immunised.

Monovalent pandemic vaccines 2009 were reported to have been received for 10% of hospitalised cases.

Most of severe and fatal cases included in the groups which were recommended influenza vaccination had not been vaccinated this season.


(?)

-
------

[Giuseppe]

EuroFlu - Weekly Electronic Bulletin - Week 18 : 02/05/2011-08/05/2011 - 13 May 2011, Issue N? 402 (extract, edited): sporadic influenza activity in European Region

[Source: EuroFlu, full page: (LINK). Extract, edited.]

EuroFlu - Weekly Electronic Bulletin - Week 18 : 02/05/2011-08/05/2011 - 13 May 2011, Issue N? 402


Sporadic influenza activity of low intensity in the WHO European Region

• This issue is based on data reported in week 18/2011 by 46 Member States in the WHO European Region.
• Consultation rates for influenza-like illness (ILI) and acute respiratory infection (ARI) are at low levels in all countries.
• Sentinel-hospital surveillance data for severe acute respiratory infection (SARI) from eight countries shows that SARI hospitalizations continue to decline.
• 2% of sentinel specimens from patients with ILI or ARI, and 4% of specimens from sentinel SARI patients tested positive for influenza.

Current situation ? week 18/2011

During week 18/2011, all but one country (Armenia) reported low influenza activity.

ILI and ARI consultation rates are below the national baselines or at pre-season levels in all 34 countries reporting clinical data.

Among 39 countries reporting on the geographical spread of influenza, 38 reported no or sporadic activity, while 1 (Armenia) reported local spread.

Only two countries reported moderate impact of influenza on their health care systems (Albania and Armenia).

This week, 8 countries reported data from sentinel hospital-based surveillance systems for SARI: Armenia, Georgia, Kazakhstan, Malta, the Republic of Moldova, Romania, the Russian Federation and Serbia.

The number of SARI hospitalizations remains at low levels in most of them. Only one country (Romania) reported influenza infection associated with a SARI case.

Further information on the sentinel SARI surveillance systems represented in the EuroFlu bulletin can be found in the ?Overview of sentinel SARI systems in EuroFlu?.



Virological situation ? week 18/2011

Sentinel physicians collected 170 respiratory specimens, of which 4 (2%) were positive for influenza B. Only one country, the Russian Federation, tested more than 20 sentinel specimens, and influenza B was detected in 3% of the samples.

In addition, 32 non-sentinel specimens were reported positive for influenza: 18 (56%) influenza A and 14 (44%) influenza B. Of the influenza A viruses, 6 were subtyped: 5 as pandemic A(H1) and 1 as A(H3).

Sentinel hospitals from 8 countries collected 56 respiratory specimens from SARI patients, of which 2 (4%) were positive for influenza B. Both cases were in Romania.



Cumulative virological update ? weeks 40/2010 ? 18/2011

A total of 82 146 influenza virus detections were reported during this period, of which 58 464 (71%) were influenza A and 23 682 (29%) were influenza B. Of the influenza A viruses, 46 507 were subtyped: 44 891 (97%) as pandemic A(H1) and 1 616 (3%) as influenza A(H3).

From week 40/2010 to week 18/2011, 1545 out of 5737 sentinel SARI specimens (27%) tested positive for influenza. Of these influenza viruses, 877 (57%) were influenza A and 668 (43%) influenza B. Of the influenza A viruses, 697 were subtyped: 644 (92%) as pandemic A(H1) and 53 (8%) as influenza A(H3).

Since week 40/2010, 5318 influenza viruses have been characterized antigenically:

• 2643 were A(H1) pandemic A/California/7/2009 (H1N1)-like;
• 2297 were B/Brisbane/60/2008-like (B/Victoria/2/87 lineage);
• 198 were B/Florida/4/2006-like (B/Yamagata/16/88 lineage);
• 174 were A(H3) A/Perth/16/2009 (H3N2)-like; and
• 6 were B/Bangladesh/3333/2007-like (B/Yamagata/16/88 lineage).

Based on the genetic characterization of 632 influenza viruses:

• 179 belonged to the pandemic A/California/7/2009 A(H1N1) cluster;
• 10 belonged to the pandemic A/Christchurch/16/2010 A(H1) cluster;
• 46 belonged to the pandemic A/Hong Kong/2213/2010 A(H1) cluster;
• 144 belonged to the A/England/142/2010 subgroup characterized by S185T substitution in the HA;
• 12 belonged to the A(H3) clade represented by A/Perth/16/2009;
• 5 belonged to the A(H3) clade represented by A/Victoria/208/2009;
• 29 belonged to the subgroup represented by A/Hong Kong/2121/2010 in the A/Victoria/208/2009 A(H3) clade;
• 23 belonged to the B/Bangladesh/3333/2007 clade (Yamagata lineage), and
• 184 to the B/Brisbane/60/2008 clade (Victoria lineage).

Since week 40/2010, 9 countries (Denmark, Germany, Ireland, Italy, the Netherlands, Norway, Spain, Switzerland and the United Kingdom) have screened 3533 viruses for susceptibility to the neuraminidase inhibitors oseltamivir and zanamivir.

The United Kingdom analysed most of the viruses screened (1672).
Of the 3169 pandemic A(H1N1) 2009 viruses that were tested, 3077 were sensitive to both inhibitors and 92 viruses (2.9%) carried the NA H275Y mutation.

These 92 viruses were resistant to oseltamivir but remained sensitive to zanamivir.

Eighteen influenza A(H3N2) viruses were tested and found to be sensitive to both inhibitors.

All of the 346 influenza B viruses tested for susceptibility to oseltamivir and the 340 tested for susceptibility to zanamivir were found to be sensitive.

All 197 pandemic influenza A(H1N1) 2009 viruses and 10 A(H3N2) viruses that were screened for susceptibility to adamantanes were found to be resistant.



Comment

ILI and ARI consultation rates are at very low levels in the WHO European Region and half of the countries reported no influenza activity this week. The percentages of sentinel samples from ILI, ARI, and SARI surveillance testing positive for influenza continue to be low.



Further information

The EuroFlu bulletin describes and comments on influenza activity in the 53 countries in the WHO European Region. For an update on the influenza situation and WHO/Europe recommendations, see the WHO/Europe web site.

Further information can be obtained from the web sites of WHO/Europe, WHO headquarters and the European Centre for Disease Prevention and Control (ECDC).

Further information on severe cases associated with influenza virus infections in the European Region can be found in the ECDC Weekly Influenza Surveillance Overview.

(?)


-
--------

[Giuseppe]

Influenza virus characterisation, summary Europe, April 2011 (ECDC, May 19 2011, extract, edited)

[Source: European Centre for Disease Prevention and Control (ECDC), full PDF document (LINK). Extract, edited.]


TECHNICAL DOCUMENT

Community Network of Reference Laboratories (CNRL) for Human Influenza in Europe

Influenza virus characterisation


Summary

Influenza A(H1N1)pdm, influenza A(H3N2), influenza B/Victoria/2/87 lineage and B/Yamagata/16/88 lineage viruses have been characterised genetically and antigenically.

• Recently isolated H1N1pdm viruses fall into several genetic groups but all groups show antigenic similarity to the currently recommended vaccine virus A/California/7/2009.
• H3N2 viruses also fall into distinct genetic groups but there is no consistent correlation between any group and antigenic differences from the currently used vaccine virus A/Perth/16/2009.
• Influenza B viruses of the B/Victoria/2/87 lineage have continued to predominate over those of the B/Yamagata/2/87 lineage. Most of the B/Victoria/2/87 lineage viruses are genetically and antigenically similar to the currently recommended vaccine virus B/Brisbane/60/2008.

Over 700 virus specimens (propagated virus isolates or clinical samples) collected since December 2010 have been received from EU and affiliated countries at the WHO CC in London (Table 1). Predominantly, these viruses were type A influenza H1N1pdm viruses and type B influenza viruses of the B/Victoria/2/87 lineage, although type A influenza H3N2 viruses and type B influenza viruses of the B/Yamagata/16/88 lineage continued to be detected. In Table 1, batches for which analysis has yet to be completed are shown as in progress.



Influenza A(H1N1)pdm virus analysis

Table 2 shows representative HI results for viruses received since the previous report. The majority of viruses continue to react well with the panel of post-infection ferret antisera, including that raised against the vaccine virus A/California/7/2009. All the viruses in Table 2 show good reactivity with all the antisera.

Nucleotide sequence analysis of the HA1 coding region of the HA gene has been carried out and a representative phylogenetic tree is shown in Figure 1. The phylogenetic tree shows residues that define four genetic groups that have been predominant over the last five months; also marked on the tree are sporadic observations of particular amino acid substitutions or polymorphisms.

As described previously (ibid) four genetic groups can be defined:

• i) A134T and S183P, now seen in at least six countries globally;
• ii) N125D, observed originally in an emerging genetic group in the Southern Hemisphere and subsequently widespread in the Northern Hemisphere;
• iii) D97N, R205K, I216V and V249L, observed in at least 10 countries;
• iv) S185T, with many viruses in this group carrying the additional substitution D97N or alternative additional substitutions of S143G and A197T, detected in most countries in Europe and the world.

The viruses highlighted in Table 2 as included in the HA gene phylogenetic analysis belong to genetic groups (iii)and (iv).

The sporadic amino acid substitutions that have been marked on the phylogenetic trees encode substitutions or polymorphisms at amino acid residues 153-157, 222 and 223. Substitutions at residues 153-157 in the HA are often associated with reduced titres in HI assays and often the substitution or polymorphism is not seen when the nucleotide sequence of the corresponding clinical specimen has been analysed. Often polymorphism at residues 153-157 is a result of cell culture.

Substitution and polymorphism at amino acid residue 222 continues to be detected and the change D222G has been postulated to be detected more often in viruses recovered from patients suffering with severe disease.
Substitutions at residue 223 (Q223R) have also been observed and are associated with isolation or propagation of the virus in hens? eggs.



Influenza A(H3N2) virus analysis

Since December 2010 influenza A(H3N2) viruses have been successfully isolated and propagated from 15 countries affiliated with ECDC. The problems with antigenic characterisation of recent H3N2 viruses have been described previously (ibid). Shown in Table 3 are the results of an HI assay using guinea pig red blood cells in the presence of oseltamivir to reduce any effect on the agglutination of the red blood cells by the virus neuraminidase (Lin et al. 2010).

The results show that, of the six viruses tested, three have a reduction in titre of eightfold with the post-infection ferret antiserum raised against the vaccine virus A/Perth/16/2009 compared with the homologous reaction between the antiserum and A/Perth/16/2009. However, all the viruses in the test reacted well with a ferret antiserum raised against A/Wisconsin/15/2009, a virus genetically and antigenically closely related to A/Perth/16/2009.

All viruses in the test showed low reactivity with antisera raised against A/Victoria/208/2009 and A/Victoria/210/2009, but these viruses show anomalously high titres with their corresponding antisera. All test viruses showed good reactivity with antisera raised against A/Alabama/5/2010 and A/Perth/10/2010.

Nucleotide sequence analysis of the HA1 coding region of the HA gene has been carried out on representative H3N2 viruses and a phylogenetic tree is shown in Figure 2. The five reference viruses and the vaccine virus A/Perth/16/2009 used in the HI test are shown in boldface type and coloured in black and red respectively.

Viruses from ECDC-affiliated countries fall into both of the genetic clades of the H3N2 HA gene, the A/Perth/16/2009 clade and the A/Victoria/208/2009 clade, with the majority of viruses falling within the A/Victoria/208/2009 genetic clade. Distinct genetic groups within the HA gene are seen within both genetic clades. As described in the last report (ibid), there are five main genetic groups that are marked on the phylogenetic tree. These groups are characterised by encoded amino acid substitutions at: within the A/Perth/16 clade, i) I260M and R261Q with E50K and P162S, and ii) N133D, R142G A212T and V213A; and, within the A/Victoria/208 clade, iii) N145S and V223I, iv) N312S, and v) D53N, Y94H, I230V, E280A and S312N.

Viruses from ECDC-affiliated countries fall into each of these genetic groups.

A correlation of the viruses analysed in the HI assay (Table 3) with the phylogenetic tree of the HA gene (Figure 2) shows that all the viruses fall into genetic group (v), but A/Genoa/01/2010, A/Lisboa/SU23/2011 and A/Valladolid/40/2011 carry the additional amino acid substitution S199A in the HA, and A/Iasi/47704/2011 carries an additional substitution I192T in the HA. Viruses in this genetic group show no consistent reduced reaction in HI assays with antisera raised against the vaccine virus and genetically closely related viruses.

Analysis of viruses from each genetic group has indicated that there is no consistent change in antigenicity associated with any emerging genetic group.



Influenza B virus analyses

As in our previous report, influenza B viruses of the B/Victoria/2/87 lineage (~ 85%) have continued to predominate over those of the B/Yamagata/16/88 lineage (~ 15%).



B/Victoria lineage viruses

Representative results of antigenic analysis of influenza B/Victoria viruses are shown in Table 4. In the HI assay some viruses showed low reactivity with antisera raised against B/Brisbane/60/2008, the egg-propagated vaccine virus. It has been known for many years that HI assays for influenza B viruses propagated only in cells frequently show reduced HI titres when tested with antisera raised against egg-propagated reference strains, including vaccine strains (Schild et al. 1983). As a consequence, the antigenic properties of cell propagated viruses are assessed with antisera raised against viruses genetically closely related to the vaccine virus but propagated in cells. In Table 4, the cell-propagated reference viruses B/Paris/1762/2008, B/Hong Kong/514/2009 and B/Odessa/3886/2010 are genetically closely related to the vaccine virus B/Brisbane/60/2008 and post-infection ferret antisera have been raised against these viruses. All the test viruses analysed in Table 4 showed good reactivity with antisera raised against these three viruses and so are considered to be antigenically similar to the vaccine virus.

Figure 3 shows a phylogenetic tree based on the HA1-coding region of the HA gene. Amino acid substitutions N75K, N165K and S172P define the B/Brisbane/60/2008 genetic clade. The vast majority of recently collected viruses from EU and affiliated countries fall into the B/Brisbane/60/2008 genetic clade. The majority of viruses carry the amino acid substitution I146V in the HA compared with the vaccine virus B/Brisbane/60/2008 and many also carry the substitution L58P. Neither substitution has a marked affect on antigenicity of the viruses.


B/Yamagata lineage viruses

Table 5 shows the results of antigenic analysis of representative recently collected influenza B/Yamagata viruses as assessed by HI assay using turkey red blood cells. The majority of the test viruses from EU and affiliated countries reacted well with the panel of antisera, but many showed markedly reduced reactivity when assessed with post-infection antisera raised against the most recently used vaccine virus of the B/Yamagata lineage, B/Florida/4/2006, an egg-propagated vaccine virus. Generally the viruses showed better reactivity with antisera raised against the reference viruses B/Bangladesh/3333/2007 and B/Wisconsin/1/2010, also propagated in hens? eggs, than they did with antisera raised against B/Florida/4/2006, with the best reactivity being seen with the post-infection antiserum raised against B/Wisconsin/1/2010.

Figure 4 shows phylogenetic analysis of the HA1 coding region of the HA gene of representative influenza B/Yamagata lineage viruses. The HA gene of all but four viruses (B/Estonia/55669/2011, B/Estonia/55763/2011, B/Finland/33/2010 and B/Finland/39/2010) fell into the B/Bangaldesh/3333/2007 genetic clade. The B/Bangaldesh/3333/2007 genetic clade is characterised by the amino acid substitutions S150I, N165Y and G229D in the HA. Minor genetic groups can be discerned within this clade, notably one genetic group is defined by the amino acid substitution M251V which is seen in combination with the substitutions G183R or T181A and K253R in some viruses; another group is characterised by the substitution N202S in the HA, with some viruses carrying the additional substitutions of either A146S or N116K; a third genetic group can be characterised by the amino acid substitution T181K. Viruses from EU and affiliated countries fell into two of the three minor genetic groups, those characterised by M251A and by T181K, as well as falling into the main B/Banglasdesh/3333/2007 genetic clade. Antigenic analysis of the two viruses from Finland shown in the phylogenetic tree (B/Finland/33/2010 and B/Finland/39/2010) has been described in a previous report. Table 5 and the results presented in the previous two reports indicate that the large majority of viruses of the B/Bangladesh genetic clade are antigenically closely related to the reference viruses B/Banglasdesh/3333/2007 and B/Wisconsin/1/2010.



Note to the figures

The phylogenetic trees were constructed using neighbour-join in MEGA4. The bars indicate the proportion of nucleotide changes in the sequence. Reference strains are viruses to which post-infection ferret antisera have been raised. The colours indicate the date of sample collection. Isolates from ECDC countries are highlighted in yellow. Sequences for some of the viruses from non-European countries were recovered from GISAID and we acknowledge all laboratories who submitted sequences directly to the London WHO CC.

(?)


-
------