Pfizer has shared positive top-line results from a late-stage trial of its respiratory syncytial virus (RSV) vaccine in adults aged 60 years and older.
RSV is a common contagious virus characterised by several mild, cold-like symptoms. There are two major subgroups of the virus, RSV A and RSV B, both of which cause disease and can co-circulate or alternate predominance from season to season.
Although most people recover within a week or two, RSV can cause severe illness in older adults, young infants and individuals with certain chronic medical conditions.
Among older adults, RSV infections account for approximately 60,000 to 160,000 hospitalisations and 6,000 to 13,000 deaths each year in the US.
Pfizer’s Abrysvo is already approved in major markets, including the US and EU, to protect older adults against RSV as well as infants through maternal immunisation.
Results from the ongoing RENOIR trial have shown that the vaccine maintained consistently high protective efficacy for both RSV A and RSV B disease through two seasons after a single dose.
Abrysvo efficacy was 77.8% against RSV lower respiratory tract disease (LRTD) with three or more symptoms in a second full RSV season in adults 60 years and older.
Consistent vaccine efficacy was demonstrated for both RSV A and RSV B after season two, with vaccine efficacy against each subtype of at least 80% for LRTD with three or more symptoms.
Vaccine efficacy was also sustained against less severe LRTD, defined by two or more symptoms, from 65.1% after season one to 55.7% after the end of season two, the company said.
Annaliesa Anderson, senior vice president and chief scientific officer, vaccine research and development at Pfizer, said: “We are encouraged by the level of protection that we observed after two full RSV seasons for Abrysvo.
“This new data indicates that broad and durable protection against both types of RSV that cause disease, RSV A and RSV B, is the potential benefit to having a bivalent vaccine.”
Pfizer has initiated two additional clinical trials evaluating Abrysvo, one in children ages two to less than 18 years who are at a higher risk for RSV disease, and another in adults ages 18 to 59 years at a higher risk for RSV due to underlying medical conditions and adults aged 18 years and older who are immunocompromised and at a high risk for RSV.