Nasal Covid-19 Vaccine Shows Promise for Sterilizing Immunity

Scientists in Germany have developed a nasal Covid-19 vaccine using a live but weakened form of the coronavirus that achieved sterilizing immunity in hamster studies. The vaccine, created through codon pair deoptimization to weaken the virus, was tested in experiments published in Nature Microbiology in April 2023. Researchers at the Max Delbruck Center for Molecular Medicine in Berlin found that two doses of the nasal vaccine created stronger immune responses than mRNA or adenovirus-based vaccines, effectively blocking viral replication in the animals' upper airways. While the vaccine used the original Covid-19 strain and showed reduced effectiveness against Omicron, researchers are working on updates. The team has partnered with Swiss company RocketVax to begin phase I human trials. This approach joins at least four other nasal vaccines in late-stage testing worldwide, including approved versions in China and India, though published effectiveness data remains limited.