The first phase of human clinical trials to study a possible nasal vaccine against COVID-19 has begun, the National Institutes of Health (NIH) announced.
The clinical trial, sponsored by the federal health agency, is enrolling participants at three sites in the United States.
Researchers believe the vaccine candidate could offer even better protection against emerging variants than injected COVID vaccines.
“We’re looking to develop next-generation vaccines,” said Dr. John Brownstein, an epidemiologist and chief innovation officer at Boston Children’s Hospital and an ABC News contributor. “Throughout the pandemic, we’ve seen incredible scientific breakthroughs with COVID vaccines, which have been brought into production very quickly and proven to be safe and effective. But of course, we also recognize that there are challenges with existing vaccines.”
Here’s what you need to know about the ongoing COVID-19 nasal vaccine clinical trial:
What is the new vaccine candidate?
The candidate, MPV/S-2P, uses a live, weakened version of a virus called murine pneumonia virus (MPV), which does not cause disease in humans.
The MPV will deliver a stabilized version of the Spike protein, which the SARS-CoV-2 virus, which causes COVID-19, uses to attach to and infect human cells. This will teach the body to recognize the protein and train immune cells to attack if a person is infected.
Preclinical trials in non-human primates have shown that MPV/S-2P is safe and well tolerated and produces a robust immune response, both in anti-SARS-CoV-2 antibodies and in epithelial cells lining the nose and airways.
“Viruses like SARS-CoV-2 enter the body through the nose, into the lungs, and then integrate into our bloodstream and spread throughout the body,” Dr. Reynold Panettieri, professor of medicine at Rutgers University’s Robert Wood Johnson Medical School, told ABC News.
“We realized that systemic vaccination — when we inject it and it goes through the body to develop immunity — is not as effective as generating immunity through the mucosal cells or the lining of the nose or the lungs,” he said. “So when people can inhale the protein, in this case the Spike protein … it actually develops a much more robust immune response than what is generated when it is injected.”
Challenges of the current vaccine
In December 2021, the U.S. Food and Drug Administration (FDA) authorized two new messenger RNA (mRNA) COVID-19 vaccines, from Pfizer-BioNTech and Moderna, to target the original variant.
While most vaccines use a weakened or inactivated virus to stimulate an immune response, mRNA vaccines teach the body to make proteins that can trigger an immune response and fight infection.
Because researchers can design mRNA vaccines faster than they can produce the live or weakened pathogens needed for a traditional vaccine, mRNA COVID-19 vaccines have been rapidly developed, tested, mass-produced and administered to the general population, preventing millions of hospitalizations and deaths, the analyses show.
Both have been updated over time to target new variants, including in September 2022 to target both the original variant and BA.4 and BA.5 – offshoots of the omicron variant – and in September 2023 to target the XBB offshoot of the omicron variant. Only the latter is currently in use.
“The current vaccines have seen their effectiveness decline over time,” Brownstein said. “These vaccines provided high protection against hospitalization and death from severe COVID-related illness, (but) they were not as effective at slowing cases and preventing transmission.”
Additionally, mRNA vaccines require a multi-step manufacturing process and very low-temperature storage, which can pose logistical challenges. Additionally, some people may not want to receive mRNA vaccines because they have an aversion to needles.
“The nasal spray is often more widely accepted by a population, so if it’s a less concerning delivery method, plus it offers better protection, plus it offers potentially better storage and distribution potential, that underscores that this could be a really important next step in controlling this virus,” Brownstein said.
How will the trial take place?
The clinical trial will enroll 60 healthy adult participants ages 18 to 64 who have received at least three doses of an FDA-approved or authorized COVID-19 mRNA vaccine.
Several trial sites will open, including Baylor College of Medicine in Houston, Texas, Emory University’s Hope Clinic in Decatur, Georgia, and New York University’s Grossman Long Island School of Medicine on Long Island.
Participants will be divided into three groups, each receiving different doses. Researchers will follow up with the volunteers seven times over the course of a year and assess whether the vaccine is safe and whether it produces an immune response in the nose and blood.
Because clinical trials take time to produce data and require at least three phases before being submitted for FDA authorization, experts say these vaccines are unlikely to be available by fall 2024.
“At the beginning of the pandemic, we moved faster than usual to distribute a vaccine,” Panettieri said. “Not that steps were skipped, but we had to save lives.”
Since COVID-19 infection now causes mild symptoms in most healthy people, “we have time to go through the usual process that the FDA goes through to approve a new treatment,” he added. “That’s going to help everybody. It’s going to be about making sure the treatment is safe and effective.”
Dr. John Beigel, associate director for clinical research in the division of microbiology and infectious diseases at the National Institute of Allergy and Infectious Diseases (NIAID), told ABC News that MPV/S-2P is part of the NextGen project.
The project, led by the Biomedical Advanced Research and Development Authority (BARDA) and NIAID, plans to support 15 next-generation vaccines in Phase 1 clinical trials, of which MPV/S-2P is the first.