Despite mass COVID-19 vaccinations worldwide (including regular booster shots with updated vaccine formulations), COVID-19 infections are still doing the rounds. Researchers have been working tirelessly to develop new options that might provide better, more extended protection than existing mRNA vaccines. Some might be on the right track.
University of Maryland researchers have launched a preclinical trial to test a next-generation nasal vaccine against COVID-19. It may currently involve only mice and hamsters, but the results show significant promise that might nudge the study toward human trials.
Here’s what mechanism the researchers used and the findings that could lead to the widespread adoption of nasal COVID-19 vaccines.
Leveraging the neonatal Fc (FcRn) receptor
Here’s what they achieved technically.
The neonatal fragment crystallisable (Fc) receptor is a protein that prevents the immunoglobulin G (IgG), the most prevalent antibody in blood circulation, from degrading. It maintains IgG levels in epithelial cells (covering your skin, organs, and blood vessels), helping your body fight infections.
Since the COVID-19 virus enters the body through airways, epithelial cells need high IgG levels to fight the infection before it reaches the bloodstream and replicates. That’s where an FcRn-targeted mucosal vaccine comes into play.
The University of Maryland researchers leveraged the FcRn receptor to make it send antibodies to epithelial cells. They bound a human IgG antibody to a SARS-CoV-2 spike before binding the resulting spike protein to the FcRn receptor. Testing the vaccine on mice and hamsters, including variants like delta and omicron, yielded encouraging results.
Promising preliminary results
And here’s the rub. In the preliminary findings, 83% to 100% of immunised mice and hamsters survived. Notably, those intranasally vaccinated showed reduced inflammation, lower viral replication, and a more robust immune response compared to the intramuscularly immunised group, typically receiving regular vaccine injections.
One significant advantage of the nasal vaccine is its ability to activate antibodies as soon as airborne particles enter the airway, effectively curbing the virus’s spread. This prompts the question…
Could nasal vaccines provide better protection than mRNA vaccines?
It is indeed possible. Nasal vaccines could be better than their mRNA counterparts. After all, they could trigger an immune response once an airborne virus enters the nose and mouth. mRNA vaccines achieve this only when the virus has already reached the bloodstream.
That could make nasal vaccines superior in fighting all kinds of respiratory infections, not only COVID-19 and its specific variants.
These reassuring results will likely spur additional studies and, when the time comes, human trials.
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