On Wednesday, researchers from the US National Institute of Health revealed that they had developed a mucosal vaccine for respiratory viruses. In their statement, they revealed that developing a vaccine against influenza, coronavirus, and respiratory syncytial virus with long-lasting protection was a challenging task.

Very short incubation periods, fast host-to-host transmission, and reproduction in the body are just a few of the traits that flu, RSV, SARS-CoV-2, and "common cold" coronaviruses all possess that allow them to cause multiple re-infections. As a result, before developing a new vaccine, more must be learned about interactions between flu viruses, coronaviruses, and RSV, and the components of the immune response that operate largely or exclusively in the upper respiratory system.

They stated that over time, immune tolerance has limited the vaccine′s activity. As a result, mucosal immunisation appears to be the most effective route of vaccination for the viruses of interest.