An intranasal vaccine booster, meaning an inoculation that is administered with a spray into the nose, is showing early promise as an added protection against SARS-CoV-2 and may become an integral part of the COVID-19 vaccine response. Researchers are looking at how creating additional antibodies in the upper airways through these sprays may offer an answer to what some may see as a nearly endless series of booster shots. What’s more, the intranasal boosters are being developed to fight multiple variants. With some of the products in clinical trials, we’ll need to ask whether a spritz up the nose will soon become just as important as that jab in the arm.
A few of our CoVaRR-Net experts are doing research here in Canada to develop these boosters, which could – with hope and, more importantly science – help people the world over. Here’s some of what they know so far.
Nasal vaccines neutralize the virus at the source of entry
A vaccine booster sprayed into the nostrils targets the coronavirus where it enters: the lining of the airways. The nasal spray vaccines create antibodies (IgA) that reside within the mucosal surfaces of the nose and throat. “Vaccine boosters sprayed up the nose could be the best way to prevent infections long term because they protect our bodies right where we need to ward off the virus: the mucosal linings of the airways, where SARS-CoV-2 first lands,” says Dr. Jennifer Gommerman, CoVaRR-Net’s Immunology & Vaccine Protection Pillar Co-Lead, Professor at the University of Toronto, and Canada Research Chair in Tissue Specific Immunity.
“What is different about these boosters is that they are highly neutralizing at the point of entry,” explains Marc-André Langlois, CoVaRR-Net’s Executive Director, a Professor at the University of Ottawa and former Canada Research Chair in Molecular Virology and Intrinsic Immunity.
A vaccine injected the traditional way, with a needle into the muscle, induces protective antibodies and lymphocytes mainly in the blood. “For current COVID-19 vaccines, this means more protection to the lungs, bronchi and heart than the upper respiratory airway, whereas the nasal boosters offer protection to all areas, and especially in the nose, mouth and throat which are the entry points where this virus first attaches itself” Dr. Langlois adds.
Nasal boosters are a response to the growing need for further immunity protection
By cutting down on infections at the point of entry, inoculating intranasally may cut down on the need for future booster shots. These types of nasal boosters are “the only way to really circumvent person-to-person transmission,” Dr. Gommerman recently told the New York Times. “We can’t live forever sheltering vulnerable people and (needle-) boosting them so that their antibody levels stay artificially high,” she adds.
There are intranasal vaccine boosters being developed that can tackle multiple variants
There are about a dozen intranasal boosters in development, some in Phase 3 trials. Many of them are designed as multivalent approaches to vaccination, meaning they offer broad protection from multiple variants by providing a larger array of epitopes, or targets, across different viral proteins that can be recognized by the immune system. “Multivalent vaccine boosters hold the promise of being effective against emerging SARS-CoV-2 variants and possibly new strains of the virus,” says Dr. Langlois. “By training the immune system to recognize different parts of the virus, not just the spike protein, it becomes much more difficult for the virus to evade detection and elimination.
These vaccines would be best employed as complementary protection
There appears to be much agreement from researchers that nasal vaccine boosters act best as a preventative measure alongside intramuscular vaccines. They likely won’t replace traditional vaccines but will offer additional benefits and protection, and leverage the existing immunity created by traditional vaccines. “These are not alternative approaches to vaccination; they are complementary,” says Dr. Mark Brockman, CoVaRR-Net’s Immunology & Vaccine Protection Pillar Deputy and Professor at Simon Fraser University. “The current vaccines are outstanding in preventing severe disease and those vaccines should continue to be deployed. However, intranasal vaccine boosters may be more adept at blocking infection and transmission of VOCs as well – something the intramuscular vaccines were not designed to do.”
Nasal vaccine boosters are painless and easier to administer
Nobody likes getting a needle, especially children. Injections also require a health professional to administer them. However, intranasal vaccines could be more easily administered en masse than booster shots, especially as they could be quickly administered and would cut down on the need for needles and syringes.
Still a ways to go
There is still more work to be done before nasal vaccines are used as complementary protection to regular vaccines, due to the complicated process involved in their development. “Measuring antibodies in the nose and mouth mucus is much more difficult than quantifying antibodies in blood,” explains Dr. Gommerman. “The number of mucosal antibodies is often low.”