Breakthroughs in RSV Prevention: Merck and Pfizer Report High Efficacy Rates

Merck's Clesrovimab (MK-1654):

Efficacy:
Clesrovimab significantly reduced RSV-associated hospitalizations by 84.2% and RSV-associated lower respiratory infection hospitalizations by 90.9% through 5 months in healthy preterm and full-term infants.

Safety:
The incidence of adverse events and serious adverse events were comparable between the clesrovimab and placebo groups, with no treatment or RSV-related deaths.

Potential:
Clesrovimab could become the first and only approved immunization designed to protect infants with the same single dose regardless of weight for the duration of their first RSV season.

Pfizer's ABRYSVO:

Efficacy:
ABRYSVO, a bivalent vaccine, showed 77.8% efficacy against RSV lower respiratory tract disease with three or more symptoms in adults 60 years and older through two full RSV seasons after a single dose.

Consistency:
ABRYSVO maintained high protective efficacy for both RSV A and RSV B disease through two seasons.

RSV Impact:

Global Burden:
RSV is a leading cause of hospitalization for healthy infants under a year old, causing an estimated 101,000 deaths a year worldwide in children under five.

Prevention Needs:
There is a high unmet need for preventative options in both healthy and high-risk infants.

Competitive Landscape:

AstraZeneca and Sanofi's Beyfortus (nirsevimab):
Beyfortus, a prophylactic antibody, has been approved for use in newborns entering their first RSV season or those up to 24 months old and at severe risk of infection entering their second RSV season. It has shown effectiveness in reducing RSV-associated hospitalizations by 90%.