New mucosal COVID vaccine, which is administered as an intranasal spray, generates strong mucosal immunity, and is much better than the mRNA COVID vaccine in preventing virus transmission (at least in hamsters, which this study used to test the vaccine).
There has been growing interest in mucosal vaccines in recent years; the mucosal immune system is one which is distinct from the systemic immune system (for one thing, the mucous membranes use IgA antibodies to fight pathogens, whereas systemic immunity uses IgM and IgG antibodies).
Mucosal vaccines can be effective because most viruses are transmitted person to person via the mucous membranes which line the respiratory and gastrointestinal tracts. When you catch a respiratory virus, it will first land on the mucous membranes in your mouth, nose, throat or gut, and start infecting the cells of the mucous membranes, before later spreading into your bloodstream and disseminating more widely in the body.
But if your mucosal defences are strong, then you can wipe out the virus before it gets a chance to disseminate more widely.
This particular intranasal COVID mucosal vaccine is based on a live attenuated COVID virus, which is an old vaccine technology. Live attenuated vaccines afford good protection, but very occasionally they can cause an actual full-blown infection, in people with weakened immunity.
It makes sense that a mucosal COVID vaccine might be better at preventing person to person transmission of SARS-CoV-2, since this virus is transmitted by saliva or nasal secretions, and the virus gets into the saliva via virally infected cells on the mucous membranes. So if you ramp up mucosal immunity, fewer viruses will be created in the mucous membranes, which equates to people becoming less infectious.
Edited by Hip, 09 February 2024 - 09:22 PM.