University of Maryland researchers develop nasal spray that may protect against Covid-19

In future Covid-19 booster rollouts, providers may be administering nasal sprays instead of vaccines in the arm.

Researchers at the University of Maryland (UMD) have developed a nasal spray that helped protect mice and hamsters against a Covid infection and reduce airborne transmission in preclinical trials, according to the study published on November 6.

“We continue to hear about new variants, and new waves of Covid-19, and to prevent this, we need a vaccine that is easy to administer and can prevent transmission,” Xiaoping Zhu, the study’s lead author and UMD veterinary medicine professor, said in a statement. “This nasal vaccine prevents virus transmission and can be easily adapted for new variants.”

The UMD researchers’ vaccine binds the Covid spike protein to a protein known as neonatal Fc receptor (FcRn) that can transport the antibodies through epithelial cells in the airways. Instead of waiting for the immune system to detect the coronavirus after it begins replicating like in intramuscular vaccines, the nasal spray prevents it from getting that far by creating an immune response in the cells lining the nose, mouth, and throat, according to the study.

The intramuscular vaccine delay is a “shortcoming [that] allows opportunistic breakthrough infections in those who received vaccinations. Hence, the SARS-CoV-2 can linger in the nasal mucosa even after clearing infection in the lungs in vaccinated individuals,” the researchers wrote. In other words, a vaccine shot in the arm cannot always provide protection against viral cells that accumulate in the nasal cavity.

As part of the study, the UMD researchers exposed mice and hamsters that were vaccinated with the nasal spray along with unvaccinated mice and hamsters to various Covid variants, including Delta and Omicron. The mice and hamsters that had received the nasal spray vaccine had a stronger immune response with more tissue-resident memory (TRM) T cells—which are essential for immune defense against pathogens like the Covid virus—compared to those that had been given the injection.

The nasal spray vaccine also reduced Covid air transmission. Researchers exposed unvaccinated hamsters to hamsters that had received the nasal spray but were also infected with Covid. After 10 days, four of the six unvaccinated hamsters exposed to the infected hamsters had “no detectable live virus,” according to the study.

The nasal spray technology isn’t limited to Covid vaccines, and could be adapted to protect against the flu or respiratory syncytial virus (RSV), the UMD researchers found.

Other researchers are also investigating the potential of Covid nasal spray vaccines. Researchers at the Dartmouth Hitchcock Medical Center (DHMC) and Dartmouth’s Geisel School of Medicine have partnered with the National Institutes of Health and biotech company Exothera to bring to market a Covid intranasal vaccine that doesn’t need refrigeration or a healthcare professional to administer it, DHMC announced in August.