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Nasal Covid vaccine shows promise in early clinical trial

Nasal vaccines could provide better protection against infection by bolstering immunity right where the virus enters the body, but few have made it to human trials in the U.S.
A researcher sprays a nasal vaccine for Covid.
Researchers at the University of Georgia are studying a nasal vaccine for Covid.University of Georgia

An experimental nasal vaccine provided strong protection against Covid infection, according to preliminary results from a Phase 1 clinical trial.

The vaccine, developed by a startup called Blue Lake Biotechnology Inc., was found to reduce the risk of symptomatic Covid infections by 86% for three months in people who received it as a booster dose. Existing booster shots in the United States reduce symptomatic infections by 43% in people 18 to 49 over one to two months, according to a study published in November by the Centers for Disease Control and Prevention.

The results from the clinical trial offer an early but tantalizing glimpse at how a next-generation Covid vaccine could be more effective at stopping the coronavirus in its tracks.

Scientists have said nasal vaccines could provide better protection against Covid compared to those that are injected into the arm.

Because these vaccines are sprayed in the nose, they are thought to more readily jump-start the immune system against respiratory viruses. Essentially, nasal vaccines bolster immune protection right where the virus enters the body, setting up a more targeted line of defense.

The idea is to give the immune system a heads-up so that the virus “won’t even have a chance to take hold,” said Dr. Benjamin Goldman-Israelow, an assistant professor of medicine at the Yale School of Medicine, who is not involved with Blue Lake’s clinical trials.

Goldman-Israelow’s own research in animals has shown similarly promising levels of protection. In a study published in October in the journal Science, he and his colleagues demonstrated that a nasal vaccine booster induced a strong immune response in the upper airway and was more effective at blocking Covid infections than vaccines injected intramuscularly.

Despite their promise, progress on nasal vaccines in the U.S. has lagged behind other countries. While several versions of a nasal vaccine are in development, most are in preclinical stages. Aside from Blue Lake's vaccine, only one other vaccine, from researchers at Mount Sinai in New York City, has reached human trials.

Nasal Covid vaccines have been approved in India, Iran and Russia, and two others are in use in China, along with an inhalable version that was approved in September for use as a booster. But, few details of their efficacy have been publicly released so far.

Phase 1 results

Blue Lake’s Phase 1 trial included 72 participants ages 18 to 55 who had already received at least two doses of mRNA vaccines, as well as unvaccinated healthy adults. The trial began in August 2021 and the scientists will continue collecting data from participants into December.

The findings, which were released earlier this month, are still preliminary, and more research involving more people is needed before broad conclusions can be drawn. But the vaccine appears to be showing promise so far.

“When we crunched the numbers, we had longer duration and better protection than mRNA vaccines — that’s very exciting,” said Biao He, founder and CEO of the Athens, Georgia-based startup and a professor of infectious diseases at the University of Georgia College of Veterinary Medicine.

“This is only Phase 1 and we need to do at least three phases, but we’re very encouraged and excited about this,” He said.

The vaccine uses a type of parainfluenza virus encoded with the coronavirus’s spike protein to train the immune system to recognize and fight it. The same parainfluenza virus, modified so that it doesn’t make people sick, is also used in vaccines administered to dogs to protect against kennel cough.

Once inhaled, bits of the virus replicate inside the nasal cavity for several days at levels that are just enough to trigger an immune response without actually getting a person sick.

This works by leveraging the finely tuned way that the respiratory system encounters and identifies foreign invaders, Goldman-Israelow said.

Unlike more “sterile” environments in the bloodstream, the nose and lungs have to look for specific danger signals to separate real threats from more innocuous substances.

“Your lungs are always encountering what you breathe in, and if they responded really violently and had intense immune responses against everything they encountered, you wouldn’t be able to breathe,” Goldman-Israelow said.

If nasal vaccines are given as boosters, the body will already be primed to recognize the coronavirus, and can thus mount a faster immune response at the site where the virus enters the body, he added.

In their Phase 1 trial, the researchers also recorded fewer side effects with their vaccine compared with shots. Some people reported flu-like symptoms such as sore arms, muscle aches and fever after receiving Covid injections, but He said Phase 1 participants experienced mild side effects like a runny nose, or none at all.

“The side effects from other vaccines may have discouraged some people from getting it, but in the testing we’ve done so far, our vaccine was very well tolerated,” he said.

The researchers are hoping to begin the next phase of clinical trials soon, He said, and are aiming to expand the study to include around 400 participants in the U.S. and Europe.

He said he hopes more positive results will spur additional funding to develop and test nasal vaccines — not just for Covid, but also other diseases.

If the current pace of vaccine development is any indication, there's reason for optimism, Goldman-Israelow said.

“Despite a huge anti-vaccine front, there’s also a lot of people who really want vaccines and want protection,” he said. “There seems to be people interested in this type of stuff and would like vaccines to work even better, and I believe there’s potential for them to work better.”

CORRECTION (Feb. 24, 2023, 5:06 p.m. ET): A previous version of this article misstated the results of the CDC study on mRNA boosters. It was 43% effective in people ages 18 to 49 over one to two months, not in people ages 65 and younger over three months.

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