Pfizer's respiratory syncytial virus (RSV) vaccine, Abrysvo, has shown promising results in a late-stage trial involving high-risk adults under the age of 60. The trial demonstrated that the vaccine was well-tolerated and induced an immune response comparable to that observed in older adults, for whom the vaccine is already approved. This development could pave the way for expanded access to RSV protection for a younger population with underlying health conditions.
Trial Details and Immune Response
The study involved 681 adults aged 18 to 59 who had conditions such as asthma, diabetes, and chronic obstructive pulmonary disease (COPD), all of which elevate the risk of severe outcomes from RSV infection. Pfizer reported that the immune response in this group was non-inferior to that seen in older adults who had previously received the vaccine. Dr. Iona Munjal, executive director of clinical vaccine R&D at Pfizer, highlighted the potential for expanding vaccine availability to a risk population that might not typically have access so soon.
Market Context and Competition
Abrysvo was launched last year for older adults and pregnant women to safeguard their babies against RSV. GSK also introduced its RSV vaccine, Arexvy, in 2023 and has since become a major player in the RSV vaccine market. GSK is also seeking to broaden the age range for its vaccine and has submitted data to the FDA for adults aged 50 to 59, with a decision expected by June 7. It remains uncertain whether Pfizer will be able to expand Abrysvo's label in time for the 2024-25 respiratory virus season.
Clinical Significance and Expert Opinion
RSV is a common respiratory virus that typically causes mild, cold-like symptoms. However, it can lead to severe illness, such as pneumonia and bronchiolitis, particularly in infants, older adults, and individuals with underlying health conditions. Pfizer estimates that high-risk individuals represent 9.5% of U.S. adults aged 18 to 49 and nearly a quarter of those between 50 and 64.
Dr. David Boulware, an infectious disease specialist at the University of Minnesota, suggests that the clinical benefit of the vaccine may vary within this high-risk group. While he believes that individuals with organ transplants, those undergoing chemotherapy, or survivors of congenital diseases would likely benefit significantly, the overall clinical benefit may be relatively low for most others in the high-risk categories.
