A new preclinical report indicates a single-dose mRNA vaccine can fully protect against lethal Andes hantavirus challenge in a Syrian hamster model. Researchers at UTMB tested intramuscular mRNA vaccine candidates encoding Andes virus envelope glycoproteins (Gn and Gc). With the goal of matching real-world outbreak constraints, they moved from a two-dose regimen to single-dose testing. The findings, published in The Lancet, showed 100% protection after one shot in the hamster model, and remaining efficacy even when the virus dose was substantially reduced. Investigators said they are working to fast-track the single-dose vaccines into human clinical trials, addressing a critical gap given that there are currently no approved vaccines or preventive therapies for Andes hantavirus.