Moderna shares decline, RSV vaccine efficacy lags behind competitors

Moderna Inc (NASDAQ: MRNA) shares dropped 11% on Wednesday after revealing that its RSV vaccine, mResvia, demonstrated 50% efficacy 18 months post-administration, compared to 81% efficacy at 3.7 months. Rival vaccines from GlaxoSmithKline (NYSE: GSK) and Pfizer (NYSE: PFE) showed higher long-term efficacy.

Presented to the CDC’s Advisory Committee on Immunization Practices, the data comes ahead of the committee’s recommendations on fall vaccinations. Approved by the FDA for adults 60 and older, mResvia aims to compete this fall with GSK and Pfizer’s vaccines, though analysts expect GSK to maintain market dominance. Despite the decline, Moderna’s stock remains up 25% year-to-date