Study of an RSV-hMPV-PIV3 Trivalent Vaccine Candidate VXB-251 in Older Adults

This study is being done to find out how safe and effective a new combined vaccine candidate, called VXB-251, is for older adults. The vaccine candidate is designed to protect against three common viruses that can cause respiratory tract infections: * RSV (respiratory syncytial virus) * hMPV (human metapneumovirus) * PIV3 (parainfluenza virus type 3) Two components of this vaccine (RSV and hMPV) have already been tested in people before, as part of another study for a two-in-one vaccine. However, this is the first time that the PIV3 component and all three components together (RSV, hMPV, and PIV3) are being tested in people. The vaccine candidate will be given as a single intramuscular injection. The study will also test unlicensed comparator vaccines and a placebo (a substance that looks like the real vaccine but doesn't contain any active ingredients) that target none, one or two of these viruses to see whether combining all three components affects safety or how well the immune system responds.

NCT Number	NCT07295028
Lead Sponsor	Sanofi
Conditions	Lower Respiratory Tract Disease, Healthy Participants
Enrollment	240 participants
Start Date	2025-11-17
Primary Completion	2026-04-21 (estimated)
Study Completion	2027-04-24 (estimated)
Updated on ClinicalTrials.gov	2026-05-20