RSV

[RSV image from NIAID]

Respiratory syncytial virus (RSV) remains a prominent global health concern. Each year, the virus is to blame for 2.1 million outpatient visits for children under 5 years old, according to CDC. Other vulnerable populations, including older adults and immunocompromised individuals, are also at risk.

Nevertheless, RSV has long been a research focus. Scientists first identified RSV in 1956. A year later, the pediatrician and virologist Robert M. Chanock linked RSV to respiratory infections in children. Attempts to develop a vaccine for the virus soon followed.

Despite numerous attempts beginning in the 1960s, an FDA-approved RSV vaccine has remained elusive until recently. Out front is GSK’s (NYSE:GSK) RSV vaccine for adults aged 60 and older, which has won the backing of an FDA advisory panel. Close behind is Pfizer’s (NYSE:PFE) single-dose vaccine for the same age group. Pfizer’s vaccine candidate also won backing from the FDA committee. In addition, Sanofi (EPA:SAN) and AstraZeneca (Nasdaq:AZN) are also in the process of developing their own RSV vaccines.

In total, 11 RSV vaccines are being actively studied in U.S. trials, according to NBC News.

The potential availability of multiple vaccine options promises to ensure broad protection against this widespread virus. The development of an RSV vaccine for young children could also be a significant breakthrough, as the virus can lead to severe respiratory complications in this age group.

Here we summarize recent progress for several notable RSV vaccine candidates:

Company

Vaccine Candidate

Clinical Trial Phase

Notes

GSK GSK3844766A Phase 3 82.6% efficacy in preventing lower respiratory tract disease in individuals aged 60 and above
Pfizer RSVpreF Phase 3 81.8% efficacy against severe medically attended lower respiratory tract illness caused by RSV in infants from birth to 90 days old; 69.4% efficacy during the first six months of life
Moderna mRNA-1345 Phase 3 83.7% efficacy against RSV-LRTD in older adults; well-tolerated with no safety concerns
AstraZeneca MEDI8897 Phase 2/3 52.1% reduction in medically attended RSV-LRTI in healthy preterm infants
Sanofi SP0274 Phase 1/2 Underway – focus on adult participants aged 18-50 in a sentinel cohort and 60 years and older in main and booster cohorts
Janssen Ad26.RSV.preF Phase 3* *Exited RSV vaccine market in 2023
Novavax ResVax Phase 3* *Development paused; 56.9% reduction in serious adverse events (SAEs) diagnosed as pneumonia confirmed by chest x-ray; 50% efficacy for all SAEs with clinical diagnosis of pneumonia; 72.9% efficacy in reducing x-ray confirmed pneumonia SAEs associated with RSV detection through 180 days of life