GSK's RSV Vaccine Arexvy Demonstrates Long-Term Protection in Phase 3 Trial

GSK has announced that a dose of its RSV vaccine provides protection against respiratory illness for up to three years, based on new data revealed at the CHEST 2024 Annual Meeting. The Phase 3 trial, named AReSVi-006, demonstrated that a dose of Arexvy was 62.9% effective over three RSV seasons in preventing lower respiratory infections. Additionally, the vaccine showed 67.4% effectiveness in preventing severe disease caused by respiratory syncytial virus (RSV).

RSV cases typically start to increase in the fall and extend through the winter, spanning several months that are described as the "season." According to Tony Wood, GSK’s Chief Scientific Officer, “This is the only RSV vaccine with efficacy and safety data available through three full seasons.” He emphasized that GSK will continue to provide long-term follow-up data to aid health authorities in establishing future revaccination schedules.

However, the protection offered by Arexvy did diminish somewhat by the third season, with efficacy dropping to 48%. Arexvy was the first RSV vaccine to receive approval and has since captured about 60% of the retail market share, outpacing vaccines from Pfizer and Moderna. Despite this market dominance, recent analyst reports indicate that there has been a slower uptake of RSV vaccines this season. Weekly prescriptions for Arexvy have dropped more than 50% compared to the previous year.

Jefferies analysts commented on this situation in a note, stating, “Every 3-year revaccination is consistent with our base case, and longer-term demonstrates a perhaps differentiated value of Arexvy vs competitors.” They also suggested that near-term sales projections might need to be revised downward.

GSK has projected that the vaccine could achieve peak revenue of £3 billion ($3.93 billion) or more. Last year, sales for Arexvy reached £1.2 billion ($1.6 billion).