Respiratory Syncytial Virus (RSV) and Vaccine

Abstract

Respiratory Syncytial Virus (RSV) is a single-stranded RNA virus belonging to the Pneumoviridae family. In healthy adults, infection typically results in mild cold-like symptoms; however, in infants and the elderly and immunocompromised patients, there is a higher risk of severe disease, resulting in a demand for the development of a vaccine. The formalin-inactivated RSV vaccine (FI-RSV), developed in the 1960s, failed to exhibit adequate efficacy and caused severe respiratory symptoms in vaccinated individuals upon natural RSV infection, with reports of fatalities. This phenomenon was later termed "vaccine-associated enhanced disease (VAED)," which resulted in a prolonged stagnation of development of the RSV vaccine. Subsequently, upon elucidation of the mechanism of VAED, it was discovered that the F protein on the virus surface plays a role in cell fusion, and particularly, the pre-fusion structure of the F protein induces effective neutralizing antibodies. In the 2010s, technologies to stabilize this pre-fusion F protein were established, resulting in marked progress in vaccine development. The development of subunit vaccines and mRNA vaccines based on the pre-fusion F protein became practical in the 2020s, and the use of monoclonal antibodies in clinical settings was initiated. However, challenges such as inadequate understanding of the epidemiology of RSV in adults and an unresolved prevention strategy for infants without underlying conditions prevail.