Why a COVID vaccine might work better in the nose

(NEXSTAR) – Scientists are hoping that a new type of vaccine under development could give us a better chance at fighting COVID-19 – without any type of vaccination.

Clinical trials are currently underway for a type of intranasal vaccine that is administered by spraying it up the nose rather than injecting it into the arm. While current vaccines and booster shots are very effective in preventing serious illness and death, there is hope that a nasal vaccine would be even better in preventing mild illness.

“These induce immunity in the lining of the nasopharynx — the site of initial virus replication — and can prevent infection and reduce transmission,” said Dr. William Moss, Professor of Epidemiology at the Johns Hopkins Bloomberg School of Public Health.

Because of the site of administration, nasal vaccines cause an immediate boost in antibodies in the mucus and nasal passages. “Mucosa immunity,” Moss explained, could prevent infection before the virus has a chance to spread throughout the body.

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

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

One nasal spray that protects against influenza, FluMist, is already approved and recommended by the Centers for Disease Control and Prevention for people ages 2 to 49.

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

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

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

However, a separate study of AstraZeneca’s vaccine found that only a minority of participants showed an immune response when given a nasal dose. They also found that immune responses were weaker than responses to intramuscular injections.

While nasal vaccine doses have already been approved for use in some other parts of the world, such as China and India, they are likely a long way off for the United States. According to NBC News, only two species have reached human trials in the US, and these are still in the early stages.

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