A single dose of an experimental respiratory syncytial virus (RSV) vaccine demonstrated 82.6% efficacy against lower respiratory tract disease in adults 60 years and older, according to data published today in the New England Journal of Medicine. The vaccine, developed by GSK, also showed 94.1% efficacy against severe RSV-related lower respiratory tract disease.
The phase 3 trial, conducted internationally, randomly assigned 24,966 participants to receive either the RSVPreF3 OA vaccine or a placebo prior to the RSV season. Researchers confirmed vaccine efficacy through reverse-transcriptase polymerase chain reaction (RT-PCR) testing, finding 7 cases of RT-PCR-confirmed RSV-related lower respiratory tract disease in the vaccine group compared to 40 in the placebo group, over a median follow-up of 6.7 months.
RSV is a significant cause of acute respiratory infection, lower respiratory tract disease, and death in older adults, for whom there is currently no licensed vaccine. The trial results indicate a substantial reduction in illness, with vaccine efficacy reaching 71.7% against RSV-related acute respiratory infection overall. The data also showed consistent efficacy regardless of RSV subtype (A or B).
According to GSK, the publication marks the first peer-reviewed release of phase 3 data for an RSV older adult vaccine candidate. Tony Wood, GSK’s Chief Scientific Officer, stated the company’s ambition is to protect older adults at risk from RSV, including those with underlying health conditions who experience the most severe outcomes.
The trial assessed safety in addition to efficacy, and initial findings indicate an acceptable safety profile. A phase 1 clinical trial of a similar mRNA-based RSV vaccine did not reveal safety concerns and demonstrated immunogenicity in both younger and older adults, inducing neutralizing antibodies against both RSV A and B subtypes that persisted for at least six months.
GSK anticipates the vaccine will be available in 2023, pending regulatory decisions in the United States, European Union, and other countries. Regulatory reviews are currently underway.
