Why getting a COVID vaccine in the nose might work better

(NEXSTAR) – Scientists are hopeful a new type of vaccine in development could give us a better shot at fighting COVID-19 — without involving any type of shot at all.

Clinical trials are underway for a type of intranasal vaccine, which is administered by spraying into the nose, not injecting into the arm. While current vaccines and boosters are very effective at preventing severe disease and death, the hope is that a nasal vaccine would be even better at preventing mild illness.

“These will induce immunity in the mucosa of the nasal pharynx – the site of initial viral replication – and may prevent infection and reduce transmission,” said Dr. William Moss, a professor of epidemiology at the Johns Hopkins Bloomberg School of Public Health.

Nasal vaccines, because of where they are administered, work to immediately strengthen antibodies in the mucus and nose. “Mucosal immunity,” Moss explained, could prevent infection before the virus is able to spread throughout the body.

“Scientists have learned that the virus first infects the nose and throat before sometimes spreading to the lungs, where severe COVID-19 can develop. But the nose and throat are difficult destinations for the SARS-CoV-2 antibodies that develop in the blood after a vaccine is injected into the arm or leg – making those hard-to-reach areas targets for better vaccines,” wrote the National Institute of Allergy and Infectious Diseases (NIAID).

Moss said he was “particularly excited” about the potential of a nasal vaccine for COVID-19.

A nasal spray that protects against influenza, FluMist, is already approved and recommended by the Centers for Disease Control and Prevention for those between 2 and 49 years old.

A Phase 1 clinical trial by Blue Lake Biotechnology found its nasal COVID vaccine reduced the risk of symptomatic infection by 86% for three months, NBC News reports.

For comparison, in a much larger study published last year, three doses of an mRNA vaccine were 61% effective at preventing a symptomatic infection with the omicron variant. Three doses were 95% effective at preventing severe outcomes, the study found.

NIAID also pointed to two recent studies that showed one dose of a nasal vaccine introduced into the respiratory tract triggered strong immune responses in hamsters and monkeys.

But a separate trial of AstraZeneca’s vaccine found only a minority of participants had an immune response when given a nasal dose. They also found immune responses were weaker than reactions to intramuscular injections.

While nasal vaccine doses have already been approved for use in some other parts of the world, like China and India, they are likely still a ways off for the United States. Only two types have reached human trials in the U.S., according to NBC News, and those are still in the early stages.

Even if it were approved, it’s not clear that enough people would get the new vaccine to make a dent in COVID-19 transmission. The bivalent booster, released last year to target the omicron variant, has only been administered to about 16% of the population, according to CDC tracking.