Decreased risk of non-influenza respiratory infection after influenza B virus infection in children

Abstract

Previous studies suggest influenza virus infection may provide temporary nonspecific immunity and hence lower the risk of non-influenza respiratory virus infection. In a randomized controlled trial of influenza vaccination, 1330 children were followed-up in 2009-2011. Respiratory swabs were collected when they reported acute respiratory illness, and tested against influenza and other respiratory viruses. We used Poisson regression to compare the incidence of non-influenza respiratory virus infection before and after influenza virus infection. Based on 52 children with influenza B virus infection, the incidence rate ratio of non-influenza respiratory virus infection after influenza virus infection was 0.47 (95% confidence interval: 0.27, 0.82) compared with before infection. Simulation suggested this incidence rate ratio was 0.87 if the temporary protection did not exist. We identified a decreased risk of noninfluenza respiratory virus infection after influenza B virus infection in children. Further investigation is needed to determine if this decreased risk could be attributed to temporary non-specific immunity acquired from influenza virus infection. This study was supported by the Research Fund for the Control of Infectious Diseases of the Health, Welfare and Food Bureau of the Hong Kong SAR Government (grant CHP-CE-03), the Theme-based Research Scheme project no. T11-712/19N from the Hong Kong Government, and the Laboratory of Excellence Integrative Biology of Emerging Infectious Diseases (research funding to SC), AXA Research Fund to SC. The funding bodies had no role in study design, data collection and analysis, preparation of the manuscript, or the decision to publish.