Keywords:
Causal inference; Children; Instrumental variable; Quasi-natural experiment; RSV infections; Seasonal influenza vaccine
Abstract:
Seasonal influenza vaccine is effective against influenza hospitalisations, but little is known about non-specific effects of the vaccine on other respiratory pathogens with similar seasonal patterns. We aimed to assess the causal impact of seasonal influenza vaccine on laboratory-confirmed hospitalisations for respiratory syncytial virus (RSV) in children using an instrumental variable strategy.