Researchers at the University of Houston are developing an experimental COVID-19 nasal vaccine that can be injected through the nostrils to fight the coronavirus.
Respiratory viruses, such as the coronavirus, enter the body through the nose. And some researchers, like the team in Houston, are interested in boosting the production of the antibodies present in the mucosal secretions in the nose.
Those antibodies are different from those produced by existing COVID-19 vaccines, which are injected into the arm with a needle, resulting in high levels of antibodies circulating in the bloodstream.
The antibodies in mucosal secretions “give you immunity right at the doorstep of the virus,” said Navin Varadarajan, a professor in the William A. Brookshire Department of Chemical and Biomolecular Engineering at the University of Houston. “So you’re trying to prevent viral infection even before it can set up shop and prevent it from getting into the lungs.”
In a study published in September in the journal iScience, Varadarajan and his colleagues showed that their intranasal vaccine, when used in mice, elicited immune responses in the nose as well as throughout the body. “We showed you don’t have to get one [type of immunity] at the expense of the other,” Varadarajan said.
Herman Staats, a professor in the department of pathology at Duke University School of Medicine, said the work is good evidence of a principled study showing that nasal immunization can trigger local mucosal immune responses.
Staats, who was not involved in the University of Houston study, studies mucosal immunity and his lab is developing methods to optimize nasal immunization.
“They’ve done a really good job of monitoring the induced immune responses,” Staats said. “But they didn’t vaccinate and then infect the animals to prove that” [the vaccine] protection against infection.
A nasal vaccine against COVID-19 could have another benefit. Some studies have shown that the amount of coronavirus present in the nostrils of vaccinated and unvaccinated people is comparable.
“If you could have a nasal vaccine that would cause this mucous membrane, [immune] response in the upper respiratory tract,” Staats said, “the hope would be that it would provide protection” against so-called “breakthrough” infections, the small percentage of cases in which vaccinated people contract COVID-19.
Staats said more follow-up studies are needed to see how long the immune response lasts after immunization with this type of nasal vaccine system. This will help determine whether booster doses may be needed, he said.
Staats said part of the challenge in developing nasal vaccines is that the vaccine pharmaceutical industry has so much experience providing safe and effective vaccines with needles.
Scientists in the field of nasal vaccine research have gone to great lengths to ensure that intranasal vaccines are safe, Staats said.
In the early 2000s, an intranasal flu vaccine administered in Europe caused a higher incidence of Bell’s palsy. Subsequent studies identified the component of the vaccine that caused the side effect.
Nasal vaccines have two components. A small, non-infectious piece of the virus — called a protein antigen — elicits an immune response that provides the protection needed to fight infection with that particular virus. And a molecule called an adjuvant helps stimulate a stronger immune response.
Staats said scientists are now particularly careful about the adjuvants they use to elicit an immune response with nasal vaccines.
Varadarajan is the co-founder of a company called AuraVax that is trying to bring the nasal vaccine into human clinical trials. The company has an exclusive licensing agreement with the University of Houston.
AuraVax also has partnerships with device manufacturers who have worked with the US Food and Drug Administration to find devices that can deliver the vaccine to people. Varadarajan said they hope to begin clinical trials by the end of the second quarter of 2022.
“The biggest challenge, of course, is the translation from animals to humans,” Varadarajan said.
But he hopes a nasal vaccine, which could be easier to ship, distribute and administer, could expand protection against COVID-19 around the world.