Respiratory Syncytial Virus Prevention in the Adult Population: State of the Art

Respiratory syncytial virus (RSV) is a common respiratory virus associated with acute respiratory infections (ARIs) in infants and older adults. RSV-related ARIs significantly affect the relevant clinical outcomes, including hospitalization and mortality, in older adults. Elderly individuals and those with chronic diseases are at a higher risk of infections with severe morbidity because of clinical frailty and deficiencies in immune responses. Prevention of respiratory viral infections in the adult population can be achieved through hygiene measures and active immunization. Several vaccination strategies have been developed, including nucleic acid, subunit, chimeric, live-attenuated, particle-based, and recombinant vaccines, with varying results. Subunit vaccines involving the RSV-fusion protein F in its prefusional (pre-F) conformation, with or without adjuvants, have demonstrated significant protection in older adults, reducing the rate of total and severe RSV-related lower tract respiratory diseases (LRTDs). Similarly, an mRNA vaccine encoding for the stabilized pre-F conformation showed a significantly reduced RSV-associated LRTDs in older adults. This evidence led to recent approval of two subunit vaccines (Arexvy and Abrysvo) and one nucleic acid-based vaccine (mResvia) by regulatory authorities. Currently, several vaccines are recommended for adults, resulting in crowded schedules. Therefore, covaccination is a potential strategy for improving vaccine adherence. The coadministration of approved RSV vaccines with seasonal influenza vaccines has been proven to be non-inferior to the immune response from sequential administration. Other vaccines coadministered against different pathogens are currently under investigation.