Researchers develop nasal COVID-19 vaccine in mice, hamsters

New variants cause increases in COVID-19 cases and hospitalizations. While the updated mRNA vaccines remain effective at preventing severe illness and death, they may not be as effective in reducing infection and transmission over time. To overcome this gap, the U.S. government initiative called Project NextGen seeks to develop an effective and safe nasal vaccine for controlling the spread of variants. The University of Maryland research team developed a nasal vaccine in mice and hamsters that meets all the criteria of Project NextGen.

A nasal vaccine for respiratory viruses would be a significant improvement over intramuscular shots because they are less invasive and stop viral particle replication in the airway before a virus can enter the bloodstream. This could improve the rate of vaccination and reduce the spread of disease. The virus that causes COVID-19 enters the body through the nose or mouth and replicates within epithelial cells, the protective cells that separate the inside body from the outside world. Vaccines that rely on a shot mainly create immunity in the bloodstream, which means the virus must enter the body and replicate in the blood before being detected by the body’s immune system. The new nasal vaccine produces immunity in the cells that line the nose, mouth and throat, preventing the virus from getting that far.

The researchers developed a nasal spray vaccine that delivers the SARS-CoV-2 spike protein into cells of the airway in mice and hamsters, triggering an immune response that significantly reduced infection and spread of COVID-19. The technology can be adapted to induce immunity to other respiratory illnesses, such as influenza and respiratory syncytial virus (RSV) infections.

Comparing results in mice that had the spike protein delivered by nasal vaccine, versus injection, the researchers found that the nasal vaccine triggered a significantly more potent immune response in the airway and lungs. Consequently, the researchers also found that the nasal vaccine, but not the intramuscular vaccine, dramatically reduced SARS-CoV-2 airborne transmission. This result is essential as inhalation represents a major transmission route for COVID-19, and airborne virus particles have the potential to linger in the air for up to 9 to 12 hours.

Project supported by National Institutes of Health NIAID, The Basil and Anne Hatziolos Scholarship Fund for Veterinary Medical Research, and the USDA ARS intramural research program funds. Photo courtesy Maryland Agricultural Experiment Station.