An experimental single-dose, intranasal Covid-19 vaccine has shown potential for full protection in mice against the lethal infectious disease, say researchers.
The experimental vaccine uses a harmless parainfluenza virus 5 (PIV5) to deliver the SARS-CoV-2 spike protein into cells where it prompts an immune response that protects against Covid-19 infection.
The study, published in the journal Science Advances, showed that the vaccine produced a localised immune response, involving antibodies and cellular immunity, that completely protected mice from fatal doses of SARS-CoV-2, the virus causing Covid-19.
The vaccine also prevented infection and disease in ferrets and, importantly, appeared to block transmission of Covid-19 from infected ferrets to their unprotected and uninfected cage-mates.
“The currently available vaccines against Covid-19 are very successful, but the majority of the world’s population is still unvaccinated and there is a critical need for more vaccines that are easy to use and effective at stopping disease and transmission,” said Paul McCray, Professor of Paediatrics-Pulmonary Medicine, and Microbiology and Immunology at the University of Iowa’s Carver College of Medicine.
“If this new Covid-19 vaccine proves effective in people, it may help block SARS-CoV-2 transmission and help control the Covid-19 pandemic,” he added.
PIV5 is related to common cold viruses and easily infects different mammals, including humans, without causing significant disease. The inhaled PIV5 vaccine developed by the team targets mucosal cells that line the nasal passages and airways. These cells are the main entry point for most SARS-CoV-2 infections and the site of early virus replication.
Viruses produced in these cells can invade deeper into the lungs and other organs in the body, which can lead to more severe disease. In addition, viruses made in these cells can be easily shed through exhalation allowing transmission from one infected person to others.
The vaccine can also be stored at normal refrigerator temperatures for up to at least three months. Because it is given intranasally, the vaccine may also be easier to administer, especially for those who have a fear of needles, the team said.
