Relating in vivo RSV infection kinetics to host infectiousness in different age groups

Respiratory syncytial virus (RSV) infections are a major public health concern for pediatric populations and older adults. Viral kinetics, the dynamic processes of viral infection within an individual over time, vary across different populations. However, RSV transmission in different age groups is incompletely understood from the perspective of individual-level viral kinetics. To explore how individual viral kinetics can be related to RSV transmission, we first fitted a mathematical model to longitudinal viral kinetic data from 53 individuals in pediatric, adult, and elderly age groups using a hierarchical Bayesian framework to estimate important viral kinetic parameters. Using a probabilistic model, we then related the within-host viral load to the probability of transmission for each age group. We found that children had higher peak viral loads and longer shedding periods compared to other age groups, suggesting a higher transmission probability in children over the infectious period. We validated our findings by comparing the estimated secondary attack rate across different age groups to empirical estimates from household transmission studies. Our work highlights the importance of age-specific considerations in understanding and managing RSV infections, suggesting that age-targeted interventions will be more effective in controlling RSV transmission.