Pfizer’s vaccine, Abrysvo, has shown potential in protecting adults aged 18 to 59 who are at an increased risk of severe illness from respiratory syncytial virus (RSV), according to data from a late-stage clinical trial. The vaccine is currently approved in the U.S., Europe, Japan, and other countries for adults aged 60 and older and expectant mothers who can pass on protection to their fetuses. However, there are no RSV vaccines approved worldwide for younger, high-risk adults.
Pfizer RSV and Its Impact
RSV is responsible for thousands of hospitalizations and deaths among older Americans and hundreds among infants each year. The virus can also cause severe illness in younger adults with weakened immune systems or underlying chronic conditions such as asthma and diabetes. Nearly 10% of U.S. adults aged 18 to 49 have a chronic condition that puts them at risk of severe RSV disease, according to Pfizer. That number rises to around 24% for those aged 50 to 64.
Expanding the Target Population
Dr. Iona Munjal, Pfizer’s executive director of clinical vaccine research and development, stated that high-risk adults aged 18 to 59 are the “next logical step” after working to drop rates of RSV disease in older populations. Pfizer is planning to submit the data to regulatory agencies and file for an expanded approval of Abrysvo for ages 18 and up. The company also intends to present final results from the trial at an upcoming scientific conference and submit them for publication in a peer-reviewed journal.
Initial Safety and Efficacy Data
Pfizer’s vaccine met the phase three trial’s main goals for efficacy and safety in high-risk adults aged 50 to 59. The company released data on a sub-study examining nearly 700 patients who are at high risk of severe RSV due to underlying medical conditions. A single dose of the vaccine elicited an immune response against RSV A and RSV B, the two major subtypes of the virus. The immune response was similar to that observed in adults 60 and above.
Competition in the RSV Market
The data comes as Pfizer tries to win more share of the RSV market after lagging behind GlaxoSmithKline last year. GSK’s RSV vaccine for adults aged 60 and above booked around £1.2 billion ($1.5 billion) in sales last year, while Pfizer’s shot recorded about $890 million in revenue in 2023.
