The FDA has granted approval to Pfizer's Abrysvo, a vaccine designed to prevent lower respiratory tract disease caused by respiratory syncytial virus (RSV) in adults aged 60 and older. This decision positions Pfizer alongside GSK, whose RSV vaccine, Arexvy, was approved earlier in May for the same indication, setting the stage for competition in a market estimated to be worth billions.
Target Population and Disease Burden
Abrysvo is indicated for use in individuals aged 60 years and older, the same population targeted by GSK's Arexvy. RSV leads to significant morbidity and mortality in this age group, with annual hospitalizations ranging from 60,000 to 160,000 and deaths numbering between 6,000 and 10,000 in the U.S. alone. Individuals with underlying health conditions such as heart or lung disease, or those who are immunocompromised, face a heightened risk of severe complications.
Clinical Efficacy of Abrysvo
The approval of Abrysvo is supported by data from the RENOIR trial, which demonstrated a 66.7% efficacy in preventing RSV-related respiratory tract infections with two or more symptoms. The vaccine also showed an 85.7% efficacy against infections presenting with three or more symptoms. These results highlight the potential of Abrysvo to mitigate the impact of RSV in older adults.
Safety Considerations and Future Directions
While both Abrysvo and Arexvy have shown promising efficacy, safety concerns have been raised. Specifically, cases of Guillain-Barré syndrome were observed in trials of both vaccines. However, Pfizer is pursuing approval for maternal use of Abrysvo to prevent RSV in newborns, an area where GSK halted trials of Arexvy due to concerns about preterm births and neonatal deaths. Pfizer is also planning trials in other populations, including healthy children, children with underlying conditions, high-risk adults, and immunocompromised adults.
Immunization Recommendations and Market Impact
Both vaccines are expected to be available for use in the fall of 2023, pending recommendations from the CDC's Advisory Committee on Immunization Practices (ACIP). The ACIP will provide guidance on the use of the vaccines, considering safety, efficacy, co-administration with other vaccines, and cost-effectiveness. The RSV vaccine market is projected to reach between $5 billion and $10 billion annually, attracting other players like Moderna and Bavarian Nordic, who are also developing RSV vaccines.
