Detailed Report on 2014-15 Influenza Virus Characteristics, and Estimates on Influenza Virus Vaccine Effectiveness from Austria’s Sentinel Physician Surveillance NetworkReport as inadecuate




Detailed Report on 2014-15 Influenza Virus Characteristics, and Estimates on Influenza Virus Vaccine Effectiveness from Austria’s Sentinel Physician Surveillance Network - Download this document for free, or read online. Document in PDF available to download.

Background

Influenza vaccine effectiveness VE is influenced by the antigenic similarity between vaccine- and circulating strains.

Material and Methods

This paper presents data obtained by the Austrian sentinel surveillance system on the evolution of influenza viruses during the season 2014-15 and its impact on influenza vaccine effectiveness in primary care in Austria as estimated by a test-negative case control design. VE estimates were performed for each influenza virus type-subtype, stratified by underlying diseases and adjusted for age, sex and calendar week of infection.

Results

Detailed genetic and antigenic analyses showed that circulating AH3N2 viruses were genetically distinct from the 2014-15 AH3N2 vaccine component indicating a profound vaccine mismatch. The Influenza AH1N1pdm09 viruses were antigenically conserved and matched the respective vaccine component. Influenza B viruses were lineage-matched B-Yamagata viruses with a clade-level variation. Consistent with substantial vaccine mismatch for the AH3N2 viruses a crude overall VE of only 47% was estimated, whereas the VE estimates for AH1N1pdm09 were 84% and for influenza B viruses 70%. Increased VE estimates were obtained after stratification by underlying diseases and adjustment for the covariates sex and age, whereby the adjustment for the calendar week of infection was the covariate exerting the highest influence on adjusted VE estimates.

Conclusion

In summary, VE data obtained in this study underscore the importance to perform VE estimates in the context of detailed characterization of the contributing viruses and also demonstrate that the calendar week of influenza virus infection is the most important confounder of VE estimates.



Author: Monika Redlberger-Fritz , Michael Kundi , Theresia Popow-Kraupp

Source: http://plos.srce.hr/



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