Modeling Respiratory Syncytial Virus Adult Vaccination in the United States with a Dynamic Transmission Model.

Abstract

Respiratory syncytial virus (RSV) is shown to cause substantial morbidity, hospitalization, and mortality in infants and older adults. Population-level modelling of RSV would allow for estimation of the full burden of disease and the potential epidemiological impact of novel prophylactics. We model the epidemiology of RSV in the US across all ages using a deterministic compartmental transmission model. Population-level symptomatic RSV acute respiratory tract infection (ARI) cases were projected across different natural history scenarios, both with and without vaccination of older adults aged ≥ 60. Impact of vaccine efficacy against ARIs and infectiousness and vaccine coverage on ARI incidence were assessed. Impact on medical attendance, hospitalization, complications, death and other outcomes were also derived. In the absence of a vaccine, we project 17.5-22.6 million symptomatic RSV ARI cases per year in ≥18-year-olds in the US, with 3.6-4.8 million/year occurring in ≥60-year-olds. Modelling indicates that up to 2.0 million symptomatic RSV ARI cases per year could be prevented in ≥60-year-olds with a hypothetical vaccine (70% vaccine efficacy against symptomatic ARI, and 60% vaccine coverage), and up to 0.69 million cases per year can be prevented in the non-vaccinated population, assuming 50% vaccine impact on infectiousness. The model provides estimated burden of RSV in the US across all age groups, with substantial burden projected specifically in older adults. Vaccination of ≥ 60 years-old population could significantly reduce the burden of disease in this population, with additional indirect effect in the < 60 years-old population due to reduced transmissibility.