An RSV vaccine already used for older adults could help protect people as young as 18 who are at increased risk of the disease, drugmaker Pfizer said in a news release Tuesday. The company said it would submit the information to the US Food and Drug Administration for potential expansion of the vaccine’s availability to people ages 18 to 59.
Pfizer’s RSV vaccine, Abrysvo, was approved for people 60 and older last year. The company said Tuesday that in a Phase 3 clinical trial of people 18 to 59, a single dose of Abrysvo demonstrated an immune response that wasn’t inferior to the response in the trial of the RSV vaccine for older adults. Additionally, one month after vaccination, trial participants had increased levels of neutralizing antibodies against the two main RSV subtypes compared with levels before vaccination, the company said Tuesday.
Pfizer said the vaccine was well-tolerated and had safety findings consistent with prior investigations of the vaccine in other groups of people. The results have not yet been peer-reviewed or published in a medical journal.
Respiratory syncytial virus, known as RSV, is a common respiratory virus that typically causes cold-like symptoms, but can be serious, especially in infants and older adults. The company said adults with certain underlying chronic conditions such as asthma, diabetes and chronic obstructive pulmonary disease are at increased risk of contracting and being hospitalized for RSV. According to Pfizer, 9.5% of adults age 18 to 49 and 24.3% of adults 50 to 64 in the US have a chronic condition that puts them at severe risk of the disease.
“These encouraging results provide evidence that ABRYSVO can help protect adults with increased risk against RSV-associated illness,” Annaliesa Anderson, a senior vice president at Pfizer and head of the company’s vaccine research and development, said in a news release. “We are excited to address a significant unmet need, pending regulatory authority approval, as ABRYSVO has the potential to become the first and only RSV vaccine for adults 18 years and older.”
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Pfizer’s RSV study is investigating the safety, tolerability and immunogenicity of the vaccine in adults at risk for RSV-associated disease. It includes a study of 681 adults age 18 to 59 with chronic conditions who received a single dose of Pfizer’s RSV vaccine or a placebo, and approximately 200 immunocompromised adults, roughly half of which were age 60 or older, who received two doses of vaccine one month apart, according the the company.
Pfizer also said it has started a trial to study the vaccine in children ages 2 through 17 who are at higher risk for RSV.
Another RSV vaccine, GSK’s Arexvy, is also available for adults age 60 and older. GSK said last fall it would seek approval for its RSV vaccine for people as young as 50 who have certain underlying medical conditions and are at increased risk from the respiratory virus.
CNN’s Amanda Musa contributed to this story.