The impacts of viral interaction on household transmission of respiratory viruses

The possibility of virus-virus interaction has been hypothesized at the population level, but there are limited data regarding the effects of viral interaction on transmission. This study used data from a prospective household cohort study to examine how viral interaction impacts transmission of influenza A virus (IAV), influenza B virus (IBV), and respiratory syncytial virus (RSV). We used two main predictors of transmission: coinfection in the index case and detection of a virus other than a primary virus of interest in the susceptible contact. Household- and individual-level analyses were conducted for IAV, IBV, and RSV. To estimate the risk of transmission within households with coinfected index cases, a household-level analysis was performed using multivariable regression with Poisson mixed effects models. To estimate an individual’s risk of transmission when multiple viruses co-circulated within their household, an individual-level analysis was performed using mixed-effects logistic regression models. Coinfection among index cases was associated with reduced transmission of IAV and RSV. Infection with a different virus among household contacts was associated with an increased risk of transmission of IAV and RSV. This study enhances the understanding of viral interaction by elucidating the potential impacts of interaction on virus transmission. These findings could have important implications for public health planning and prevention efforts.