A briefing document released by the FDA ahead of the Vaccine and Related Biological Products Advisory Committee revealed that a phase 1 trial evaluating two RSV vaccines in infants aged 5 to 8 months was paused in July after five severe cases of RSV-related illness were reported among infants receiving the vaccine candidates.
The trial, which tested two Moderna RSV vaccines, mRNA-1365 and mRNA-1345, found that infants who received a 15-microgram dose of either vaccine had a higher incidence of severe lower respiratory tract infections compared to those who received a placebo. Five of six infants required hospitalization, with one needing mechanical ventilation.
The safety signal prompted Moderna to halt enrollment in the trial and the FDA subsequently issued a clinical hold.
VRBPAC will review the safety data and discuss implications for the future development of RSV vaccines for infants Dec. 12.
