Seasonal influenza vaccination and the risk of infection with pandemic influenza: a possible illustration of non-specific temporary immunity following infection
Date
2010
Authors
Kelly, H
Barry, Steven
Laurie, Karen
Mercer, Geoffry
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Centre European pour la Surveillance Epidemiologique du SIDA
Abstract
Four Canadian studies have suggested that receipt of seasonal influenza vaccine increased the risk of laboratory- confirmed infection with 2009 pandemic influenza A(H1N1). During the influenza season of 2009 in Victoria, Australia, this virus comprised 97% of all circulating influenza viruses for which sub-typing was available. We found no evidence that seasonal influenza vaccine increased the risk of, or provided protection against, infection with the pandemic virus. Ferret experiments have suggested protection against pandemic influenza A(H1N1) 2009 from multiple prior seasonal influenza infections but not from prior seasonal vaccination. Modelling studies suggest that influenza infection leads to heterosubtypic temporary immunity which is initially almost complete. We suggest these observations together can explain the apparent discrepant findings in Canada and Victoria. In Victoria there was no recent prior circulation of seasonal influenza and thus no temporary immunity to pandemic influenza. There was no association of seasonal influenza vaccine with pandemic influenza infection. In Canada seasonal influenza preceded circulation of the pandemic virus. An unvaccinated proportion of the population developed temporary immunity to pandemic influenza from seasonal infection but a proportion of vaccinated members of the population did not get seasonal infection and hence did not develop temporary immunity to pandemic influenza. It may there fore have appeared as if seasonal vaccination increased the risk of infection with pandemic influenza A(H1N1) virus.
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Keywords
Keywords: alpha interferon; cytokine; human interferon; influenza vaccine; interferon; adaptive immunity; article; cellular immunity; cross protection; disease transmission; geographic distribution; human; humoral immunity; infection rate; infection risk; influenza
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Source
Eurosurveillance (Online Edition)
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Journal article
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2037-12-31
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