Thread by @sailorrooscout

THIS IS HUGE! A new nasal COVID-19 vaccine BLOCKS transmission of the virus, according to a recent study out of Washington University. This suggests vaccines delivered directly to the nose or mouth could play a critical role in containing the spread of respiratory infections.🧵⬇️

The study has been published in Science Advances.
•science.org/doi/10.1126/sc…

A new study by researchers at Washington University School of Medicine in St. Louis indicates that next-generation vaccines that target the virus’s points of entry- the nose and mouth- may be able to do what traditional shots cannot: contain the spread of respiratory infections

AND prevent transmission.

Using a nasal COVID-19 vaccine based on Washington University technology, approved for use in India and licensed to Ocugen for further development in the U.S., the researchers showed that vaccinated hamsters that developed infections did not pass the

virus on to others, BREAKING the cycle of transmission. In contrast, an approved COVID-19 vaccine that is injected failed to prevent the spread of the virus.

The findings, published July 31st in Science Advances, provide further evidence that so-called mucosal vaccines sprayed

into the nose or dropped into the mouth may be the key to controlling respiratory infections such as influenza and COVID-19 that continue to circulate and cause significant illness and death.

For this study, researchers developed and validated a model for community transmission using hamsters and then used it to assess the effect of mucosal vaccination on the spread of SARS-CoV-2. (Unlike mice, hamsters are naturally susceptible to infection with SARS-CoV-2,

making them the ideal laboratory animals for a transmission study.)

The researchers immunized groups of hamsters with laboratory versions of approved COVID-19 vaccines: the nasal iNCOVACC used in India or the injected Pfizer vaccine. For comparison, some hamsters were not

immunized. After giving the vaccinated hamsters a few weeks for their immune responses to fully mature, the researchers infected other hamsters with SARS-CoV-2 and then placed the immunized hamsters with the infected hamsters for eight hours. This first step of the experiment

mimics the experience of vaccinated people who are exposed to a person with COVID-19.

After spending eight hours rubbing shoulders with infected hamsters, most of the vaccinated animals became infected. Virus was found in the noses and lungs of 12 of 14 (86%) hamsters that had

received the nasal vaccine, and 15 of 16 (94%) hamsters that had received the injected vaccine. Importantly, while most animals in both groups were infected, they weren’t infected to the same degree. Hamsters that had been nasally immunized had virus levels in the airways

100 to 100,000 times lower than those that had received the shot or had not been vaccinated. The study did not assess the animals’ health, but previous studies have shown that both vaccines reduce the likelihood of severe illness and death from COVID-19.

The second step of the experiment yielded even more striking results. The researchers took vaccinated hamsters that subsequently developed infections and placed them with healthy vaccinated and unvaccinated hamsters for eight hours to model transmission of virus from a vaccinated

person to others.

None of the hamsters that were exposed to nasally vaccinated hamsters became infected, regardless of whether the recipient hamster had been vaccinated or not. In contrast, roughly half of the hamsters that were exposed to hamsters vaccinated by injection

became infected- again, regardless of the recipient’s immunization status. In other words, vaccination through the nose BROKE the cycle of transmission. You can read all this and more here:
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•science.org/doi/10.1126/sc…
medicine.wustl.edu/news/nasal-cov…