tetano
Editor, Senior Moderator
PLoS One. 2012;7(1):e30018. Epub 2012 Jan 10.
Effect of Vaccines and Antivirals during the Major 2009 A(H1N1) Pandemic Wave in Norway - And the Influence of Vaccination Timing.
Freiesleben de Blasio B, Iversen BG, Scalia Tomba G.
Source
Department of Biostatistics, Institute of Basic Medical Science, University of Oslo, Oslo, Norway.
Abstract
To evaluate the impact of mass vaccination with adjuvanted vaccines (eventually 40% population coverage) and antivirals during the 2009 influenza pandemic in Norway, we fitted an age-structured SEIR model using data on vaccinations and sales of antivirals in 2009/10 in Norway to Norwegian ILI surveillance data from 5 October 2009 to 4 January 2010. We estimate a clinical attack rate of approximately 30% (28.7-29.8%), with highest disease rates among children 0-14 years (43-44%). Vaccination started in week 43 and came too late to have a strong influence on the pandemic in Norway. Our results indicate that the countermeasures prevented approximately 11-12% of potential cases relative to an unmitigated pandemic. Vaccination was found responsible for roughly 3 in 4 of the avoided infections. An estimated 50% reduction in the clinical attack rate would have resulted from vaccination alone, had the campaign started 6 weeks earlier. Had vaccination been prioritized for children first, the intervention should have commenced approximately 5 weeks earlier in order to achieve the same 50% reduction. In comparison, we estimate that a non-adjuvanted vaccination program should have started 8 weeks earlier to lower the clinical attack rate by 50%.In conclusion, vaccination timing was a critical factor in relation to the spread of the 2009 A(H1N1) influenza. Our results also corroborate the central role of children for the transmission of A(H1N1) pandemic influenza.
PMID:
22253862
[PubMed - in process]
PMCID: PMC3254636
Free full text
http://www.ncbi.nlm.nih.gov/pubmed/22253862
Effect of Vaccines and Antivirals during the Major 2009 A(H1N1) Pandemic Wave in Norway - And the Influence of Vaccination Timing.
Freiesleben de Blasio B, Iversen BG, Scalia Tomba G.
Source
Department of Biostatistics, Institute of Basic Medical Science, University of Oslo, Oslo, Norway.
Abstract
To evaluate the impact of mass vaccination with adjuvanted vaccines (eventually 40% population coverage) and antivirals during the 2009 influenza pandemic in Norway, we fitted an age-structured SEIR model using data on vaccinations and sales of antivirals in 2009/10 in Norway to Norwegian ILI surveillance data from 5 October 2009 to 4 January 2010. We estimate a clinical attack rate of approximately 30% (28.7-29.8%), with highest disease rates among children 0-14 years (43-44%). Vaccination started in week 43 and came too late to have a strong influence on the pandemic in Norway. Our results indicate that the countermeasures prevented approximately 11-12% of potential cases relative to an unmitigated pandemic. Vaccination was found responsible for roughly 3 in 4 of the avoided infections. An estimated 50% reduction in the clinical attack rate would have resulted from vaccination alone, had the campaign started 6 weeks earlier. Had vaccination been prioritized for children first, the intervention should have commenced approximately 5 weeks earlier in order to achieve the same 50% reduction. In comparison, we estimate that a non-adjuvanted vaccination program should have started 8 weeks earlier to lower the clinical attack rate by 50%.In conclusion, vaccination timing was a critical factor in relation to the spread of the 2009 A(H1N1) influenza. Our results also corroborate the central role of children for the transmission of A(H1N1) pandemic influenza.
PMID:
22253862
[PubMed - in process]
PMCID: PMC3254636
Free full text
http://www.ncbi.nlm.nih.gov/pubmed/22253862