New RSV therapies may accelerate the emergence of drug-resistant strains, says analyst

Given the large market potential and high unmet need for new respiratory syncytial virus (RSV) therapies, drug developers have been focused on new vaccine and monoclonal antibody (MAb) development.

A vaccine for RSV has yet to be approved anywhere around the globe. However, recent advances in the field have led to the priority review of Pfizer (NYSE: PFE) and GSK's (LSE: GSK) vaccines for older adults, which recently gained positive recommendations from the US Food and Drug Administration’s (FDA) Vaccines and Related Biological Products Advisory Committee. Despite their benefits, new RSV therapies may accelerate the emergence of drug-resistant strains, according to analytics company GlobalData.

In November 2022, AstraZeneca (LSE: AZN) and Sanofi's (Euronext: SAN) new MAb, Beyfortus (nirsevimab), was also approved for use in infants in the European Union and the UK. Prior to the recent developments, AstraZeneca's Synagis (palivizumab), approved in 1998 to prevent RSV in high-risk infants, was the only approved option and dominated the global RSV market. However, this has caused RSV to mutate, resulting in palivizumab-resistant RSV strains.