[Peter Hansen/Adobe Stock]
GSK (NYSE:GSK) has secured FDA approval for its respiratory syncytial virus (RSV) vaccine Arexvy, marking a significant milestone in the RSV vaccine landscape. RSV is common and usually results in mild infections, but can be dangerous in the immunocompromised as well as in younger and older populations.
The GSK vaccine targets adults aged 60 and older. In clinical studies, the single-dose vaccine demonstrated strong efficacy in preventing lower-respiratory tract infections and more severe diseases. In a phase 3 study published in NEJM with a median follow-up of 6.7 months, the vaccine efficacy against RT-PCR-confirmed RSV-related lower respiratory tract disease was 82.6%.
Efficacy against severe RSV-related lower respiratory tract disease was higher at 94.1% while efficacy against RSV-related acute respiratory infection was 71.7%. The most commonly reported side effects of Arexvy were injection site pain, fatigue, muscle pain, headache and joint stiffness/pain.
GSK reported a few cases of atrial fibrillation, acute disseminated encephalomyelitis (ADEM) and Guillain-Barré syndrome in trial participants. The FDA is requiring a postmarketing study to gauge the risks for ADEM and Guillain-Barré syndrome.
A second RSV vaccine could hit the U.S. market soon as FDA is planning on deciding later in May whether to approve Pfizer’s RSVpreF vaccine.
The CDC advisory committee has scheduled to review both vaccines in June, potentially making them available before fall, when RSV outbreaks begin to be more likely. The RSV vaccine market could ultimately be worth more than $10 billion, with GSK, Pfizer and Moderna poised to be early leaders.
The following table provides an update of the RSV vaccine landscape, including the current clinical trial phases and relevant notes about their efficacy and target populations. Janssen has halted its RSV development plans while Novavax has paused theirs.
| Company | Vaccine Candidate | Clinical Trial Phase | Notes |
|---|---|---|---|
| Moderna | mRNA-1345 | Phase 3 | 83.7% efficacy against RSV-LRTD in older adults, well-tolerated with no safety concerns |
| GSK | Arexvy (GSK3844766A) | FDA approved | For individuals aged 60 and above, the efficacy rate of preventing lower respiratory tract disease is 82.6%. |
| Pfizer | RSVpreF | Phase 3 | The vaccine was found to be 81.8% effective against severe medically attended lower respiratory tract illness caused by RSV in infants from birth to 90 days old. Additionally, the vaccine showed a high efficacy rate of 69.4% during the first six months of life. FDA is set to decide whether to approve the vaccine in 2023. |
| Sanofi | SP0274 | Phase 1/2 | Underway. Focus is on adults 18 to 50 old in a sentinel cohort and 60 years and older in main and booster cohorts |