New Duke University-led Study Shows That Vaxart's Oral COVID-19 Vaccine Candidate Reduces Airborne Transmission of SARS-CoV-2 Infection in Animal Model
October 7, 2021 at 4:13 PM EDT
Data published in bioRxiv confirmed previous findings suggesting mucosal vaccines could reduce transmission of airborne viruses such as COVID-19 and flu more than injectable vaccines
Study suggests mucosal vaccines may protect not only vaccinated, but also unvaccinated animals
SOUTH SAN FRANCISCO, Calif., Oct. 7, 2021 /PRNewswire/ -- A Duke University-led study published in bioRxiv showed that Vaxart, Inc.'s (NASDAQ: VXRT) investigational oral tablet vaccine reduced the airborne transmission of SARS-CoV-2 virus in an animal model.
These results are consistent with those from Vaxart's Phase II human flu challenge study, which showed that Vaxart's oral tablet vaccine was better at reducing shedding than the injectable flu vaccine comparator.
A limitation of the currently approved injected COVID-19 vaccines is that airborne transmission occurs in people who have received them. The preclinical study also demonstrated that Vaxart's oral vaccine platform induces robust systemic and mucosal responses.
Researchers vaccinated hamsters orally or intranasally with Vaxart's S-only vaccine candidate and then exposed them to significant levels of the COVID-19 virus to promote vaccine breakthrough. Vaccinated hamsters cleared infectious virus in the nose and lungs quickly. Before clearing the infection, the vaccinated hamsters were exposed to unvaccinated hamsters via aerosol. The mucosally vaccinated hamsters infected fewer hamsters and created less severe clinical symptoms than did unvaccinated hamsters.
"These findings show that our vaccine candidate can reduce transmission of SARS-CoV-2, even when there is infection breakthrough in vaccinated subjects," said Dr. Sean Tucker, the study's lead author and Chief Scientific Officer at Vaxart.
"Existing injected vaccines don't always protect against viral shedding and transmission to other people. A vaccine that reduces shedding and reduces the probability of infection could make a big difference in protecting lives and public health, particularly given the large number of unvaccinated individuals. This study used the same vaccine candidate Vaxart is using in its development of an oral tablet vaccine," added Dr. Tucker.
Earlier this week, Vaxart initiated recruiting for a global Phase II clinical trial of its oral tablet COVID-19 vaccine candidate, which targets the SARS-CoV-2 viral spike (S) protein.
"Vaxart previously published data from a human influenza challenge study that demonstrated our oral flu vaccine candidate inhibited shedding of viral RNA better than injectable vaccines. The data reported provides further evidence that our oral vaccine could offer both an easier, more attractive mode of administration and potentially superior protection against respiratory viruses," said Andrei Floroiu, Vaxart's Chief Executive Officer.
The mucosal surface of the upper respiratory tract is the initial site of SARS-CoV-2 replication and the primary site of infection. Vaccines that induce robust mucosal immune responses may have the greatest impact on reduction of SARS-CoV-2 transmission. Approved COVID-19 vaccines, all of which are administered via intramuscular injection, stimulate systemic immune responses but have minimal effects on mucosal immunity.
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