Nasal Vaccines May Provide Additional Immune Support Against Respiratory Viruses

Intranasal vaccination may provide broad-based protection against heterologous respiratory viruses based on early results in mice, whereas injection-based vaccination did not have the same effect, according to a study published in Science Immunology.

Mucus membranes have a unique defense system for combatting airborne or foodborne pathogens. Immune B cells secrete immunoglobin A (IgA) antibodies, which work locally on mucosal surfaces in the nose, stomach, and lungs. The investigators sought to establish whether triggering IgA response might also produce a localized immune response against respiratory viruses.

“The best immune defense happens at the gate, guarding against viruses trying to enter,” said Akiko Iwasaki, PhD, the Waldemar Von Zedtwitz Professor of Immunobiology at Yale, in a press release

To conduct the study, investigators tested a protein-based vaccine designed to jump start an IgA immune response. This vaccine was administered to mice, either intramuscularly or intranasally.

These mice were then exposed to multiple strains of influenza viruses. According to the investigators, the mice that received intranasal vaccination were significantly better protected against respiratory influenza than those who received injections.

Further, these nasal vaccines induced antibodies that protected the mice against a variety of flu strains, not just against the strain the vaccine was meant to protect against. This was not observed in the population that received the vaccine through a shot.

Currently, the investigators are testing nasal vaccine strains against COVID-19 in animal models. Although both the vaccine injections and nasal vaccines increased levels of antibodies in the blood of the mice, only the nasal vaccine enabled IgA secretion into the lungs.

If these nasal vaccines are proven safe and efficient in humans, the investigators said they expect them to be used in conjunction with existing vaccines and boosters that work system wide. This method would allow the body to add immune system support at the source of infection, according to the study.

REFERENCE

Nasal vaccine may aid fight against new viral variants [news release]. EurekAlert; December 10, 2021. Accessed December 13, 2021. https://www.eurekalert.org/news-releases/937314