tetano
Editor, Senior Moderator
Clin Infect Dis. 2012 Apr 26. [Epub ahead of print]
A Sentinel Platform to Evaluate Influenza Vaccine Effectiveness and New Variant Circulation, Canada 2010-11 Season.
Skowronski DM, Janjua NZ, De Serres G, Winter AL, Dickinson JA, Gardy JL, Gubbay J, Fonseca K, Charest H, Crowcroft NS, Fradet MD, Bastien N, Li Y, Krajden M, Sabaiduc S, Petric M.
Source
British Columbia Centre for Disease Control, Vancouver, British Columbia, Canada.
Abstract
BackgroundDuring the 2010-11 winter, an excess number of long-term-care-facility outbreaks due to influenza A/H3N2, including higher-than-expected attack rates among vaccinated staff, were reported in some regions of Canada. Interim analysis from the community-based sentinel surveillance system showed circulating H3N2 variants and suboptimal vaccine effectiveness(VE), assessed here for the entire season's dataset.MethodsNasal/nasopharyngeal swabs and epidemiologic details were collected from patients presenting to sentinel sites within 7days of influenza-like-illness onset. Cases tested positive for influenza by RT-PCR; controls tested negative. Odds ratios(OR) for medically-attended laboratory-confirmed influenza in vaccinated versus non-vaccinated participants were used to derive adjusted-VE. Viruses were characterized by hemagglutination-inhibition(HI), and the hemagglutinin genes of multiple isolates were sequenced to explore vaccine-relatedness.ResultsFinal 2010-11 VE analysis included 1718 participants(half aged 20-49years), 93 with A(H1N1)pdm09,408 A/H3N2, and 199 influenza B. Among adults 20-49years, adjusted-VE was 65%(95%CI 8-87%) for A(H1N1)pdm09 and 66%(10-87%) for influenza B. VE was substantially lower for A/H3N2, at 39%(0-63%). Phylogenetic analysis identified two circulating H3N2 variant clades, A/HongKong/2121/2010 (87%) and A/Victoria/208/2009 (11%), bearing multiple amino-acid substitutions at antigenic sites(12 and 8, respectively) compared to the H3N2 vaccine component used in Canada(A/Victoria/210/2009(NYMC X-187)). However, HI characterized all H3N2 isolates as well-matched to vaccine.ConclusionsPublic health observations of increased facility H3N2 outbreaks were consistent with the sentinel network's detection of genetic variants and suboptimal VE, but not with conventional HI characterization. We highlight the utility of a multi-component sentinel surveillance platform that incorporates genotypic, phenotypic and epidemiologic indicators into the assessment of influenza virus, new variant circulation, vaccine-relatedness, and VE.
PMID:
22539661
[PubMed - as supplied by publisher]
http://www.ncbi.nlm.nih.gov/pubmed/22539661
A Sentinel Platform to Evaluate Influenza Vaccine Effectiveness and New Variant Circulation, Canada 2010-11 Season.
Skowronski DM, Janjua NZ, De Serres G, Winter AL, Dickinson JA, Gardy JL, Gubbay J, Fonseca K, Charest H, Crowcroft NS, Fradet MD, Bastien N, Li Y, Krajden M, Sabaiduc S, Petric M.
Source
British Columbia Centre for Disease Control, Vancouver, British Columbia, Canada.
Abstract
BackgroundDuring the 2010-11 winter, an excess number of long-term-care-facility outbreaks due to influenza A/H3N2, including higher-than-expected attack rates among vaccinated staff, were reported in some regions of Canada. Interim analysis from the community-based sentinel surveillance system showed circulating H3N2 variants and suboptimal vaccine effectiveness(VE), assessed here for the entire season's dataset.MethodsNasal/nasopharyngeal swabs and epidemiologic details were collected from patients presenting to sentinel sites within 7days of influenza-like-illness onset. Cases tested positive for influenza by RT-PCR; controls tested negative. Odds ratios(OR) for medically-attended laboratory-confirmed influenza in vaccinated versus non-vaccinated participants were used to derive adjusted-VE. Viruses were characterized by hemagglutination-inhibition(HI), and the hemagglutinin genes of multiple isolates were sequenced to explore vaccine-relatedness.ResultsFinal 2010-11 VE analysis included 1718 participants(half aged 20-49years), 93 with A(H1N1)pdm09,408 A/H3N2, and 199 influenza B. Among adults 20-49years, adjusted-VE was 65%(95%CI 8-87%) for A(H1N1)pdm09 and 66%(10-87%) for influenza B. VE was substantially lower for A/H3N2, at 39%(0-63%). Phylogenetic analysis identified two circulating H3N2 variant clades, A/HongKong/2121/2010 (87%) and A/Victoria/208/2009 (11%), bearing multiple amino-acid substitutions at antigenic sites(12 and 8, respectively) compared to the H3N2 vaccine component used in Canada(A/Victoria/210/2009(NYMC X-187)). However, HI characterized all H3N2 isolates as well-matched to vaccine.ConclusionsPublic health observations of increased facility H3N2 outbreaks were consistent with the sentinel network's detection of genetic variants and suboptimal VE, but not with conventional HI characterization. We highlight the utility of a multi-component sentinel surveillance platform that incorporates genotypic, phenotypic and epidemiologic indicators into the assessment of influenza virus, new variant circulation, vaccine-relatedness, and VE.
PMID:
22539661
[PubMed - as supplied by publisher]
http://www.ncbi.nlm.nih.gov/pubmed/22539661