In a new study that evaluated the potential of a single-dose intranasal Covid-19 vaccine, a team from the University of Iowa and the University of Georgia found that the vaccine fully protects mice against lethal Covid-19 infection. The vaccine also blocks the transmission of the virus from animal to animal. The findings were published July 2 in the journal Science Advances.
“Currently available vaccines against Covid-19 are very successful, but the majority of the world’s population has not yet been vaccinated and there is a critical need for more vaccines that are easy to use and effective in stopping disease and transmission,” said Paul McCray , MD, professor of pediatric-pulmonary medicine and microbiology and immunology at UI Carver College of Medicine, and co-leader of the study. “If this new vaccine proves effective in people, it could help block transmission and help control the pandemic.”
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Unlike traditional vaccines that require an injection, this vaccine is administered via a nasal spray. The vaccine used in the study requires only a single dose and can be stored at normal refrigerator temperature for up to three months. Because it is administered intranasally, the vaccine can also be easier to administer, especially for those who are afraid of needles.
The experimental vaccine uses a harmless parainfluenza virus 5 (PIV5) to deliver the spike protein SARS-CoV-2 into cells, where it stimulates an immune response that protects against Covid-19 infection. PIV5 is related to common cold viruses and easily infects different mammals, including humans, without causing significant illness. The research team has already shown that this vaccine platform can completely protect experimental animals from another dangerous coronavirus disease called Middle East Respiratory Syndrome (MERS).
The inhaled PIV5 vaccine developed by the team targets the mucosal cells that line the nasal passages and airways. These cells are the main entry point for most SARS-CoV-2 infections and the initial replication site for the virus. Viruses produced in these cells can deeply invade the lungs and other organs of the body, which can lead to more serious illness. The study showed that the vaccine produced a localized immune response, involving antibodies and cellular immunity, that completely protected the mice from fatal doses of SARS-CoV-2. The vaccine also prevented infection and disease in ferrets and, more importantly, appeared to block the transmission of COVID-19 from infected ferrets to their unprotected and uninfected cagemates.
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