Can The Mucosal Immunity Protect Against COVID-19?

In addition to the complexity of IgA tests, intranasal vaccines have another drawback. “It is actually quite difficult to get the nasal spray to stay in the nasal tract,” says Victoria Kett, a drug delivery scientist at Queen’s University Belfast who has worked on intranasal vaccines. “If you use a nasal spray, it often doesn’t take long before you can taste it. And if you can taste it, it has left your nose,” Herman Ford Staats, immunologist, Duke University School of Medicine, says. Another risk of intranasal vaccines is sneezing. You take only a deep breath and sneeze the dose right out. All this means that researchers aren’t sure of the exact dose a person receives. 

These considerations explain why up to the present, pharmaceutical companies have been reluctant to invest in the needle-free approach. 

Nevertheless, some immunologists think the mucosal immune system has been seriously underestimated. Recently, it has been demonstrated that in the absence of local (mucosal) immunity, the nasal cavity may become a reservoir for the coronavirus, putting the patient at risk for reinfection or disease transmission to others. Mucosal immunity can stop both infections and the spread of the virus. However, mucosal immunity needs triggering. “…if you don’t stimulate the immune system in the mucosae, you don’t obtain mucosal immune responses,” says Pierre Charneau, head of the Molecular Virology and Vaccinology Unit at the Pasteur Institute. It is very important that mucosal immunity can only be achieved by administering a vaccine intranasally, not intramuscularly.