Introduction
Respiratory syncytial virus (RSV) is a leading cause of seasonal respiratory infections, particularly affecting older adults and those with chronic cardiopulmonary conditions. Each year in the United States, RSV accounts for an estimated 100,000 to 150,000 hospitalizations and 4,000 to 8,000 deaths among adults aged 60 years and older. In response to this significant disease burden, three RSV vaccines targeting the RSV prefusion F protein have been licensed for adults aged 60 years or older. Two protein subunit vaccines, Arexvy (GSK) and Abrysvo (Pfizer), were introduced in 2023, with an mRNA vaccine, mRESVIA (Moderna), approved in 2024.
Initial recommendations advised a single dose for adults aged 60+ based on clinical judgment, evolving by June 2024 into a universal recommendation for adults 75+ and a risk-based approach for 60 to 74-year-olds at increased risk. Duration of protection and optimal revaccination intervals remain unclear, highlighting a critical need to evaluate vaccine effectiveness (VE) in real-world settings beyond clinical trials.
