Indirect Protection from Vaccinating Children against Influenza A Virus Infection in Households |
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| Authors: | Tim K. Tsang Can Wang Vicky J. Fang Ranawaka A. P. M. Perera Hau Chi So Dennis K. M. Ip J. S. Malik Peiris Gabriel M. Leung Simon Cauchemez Benjamin J. Cowling |
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| Affiliation: | 1.WHO Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China;2.Laboratory of Data Discovery for Health Limited, Hong Kong Science and Technology Park, New Territories, Hong Kong, China;3.HKU-Pasteur Research Pole, The University of Hong Kong, Hong Kong, China;4.Mathematical Modelling of Infectious Diseases Unit, Institut Pasteur, UMR2000, CNRS, 75015 Paris, France |
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| Abstract: | Influenza vaccination is an important intervention to prevent influenza virus infection. Our previous analysis suggested that indirect protection is limited in an influenza B epidemic in Hong Kong. We further analyzed six influenza A epidemics to determine such potential. We applied a statistical model to estimate household transmission dynamics in the 3 influenza A(H3N2) and 3 pandemic influenza A(H1N1) epidemics. Then, we estimated the reduction in infection risk among unvaccinated household members when all children in households are vaccinated, with different assumptions on vaccine efficacy (VE). In the optimal scenario that VE was 70%, the reduction to the total probability of infection was only marginal, with relative probabilities ranged from 0.91–0.94 when all children in households were vaccinated because community was by far the main source of infection during the six epidemics in our study. The proportion of cases attributed to household transmission was 10% (95% CrI: 7%, 13%). Individual influenza vaccination is important even when other household members are vaccinated, given the degree of indirect protection is small. |
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| Keywords: | influenza vaccination indirect protection |
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