Vaxart, Inc. reported positive preliminary preclinical data demonstrating that two COVID-19 vaccine candidates targeting either the SARS-CoV-2 spike (S) protein for Wuhan or S protein for Omicron protected hamsters when challenged with the Omicron BA.1 variant.
“Approved COVID-19 vaccines afford less protection against infection from new SARS-CoV-2 variants compared with the original parental strain against which they were developed. A broadly cross-reactive vaccine may be the most effective way to protect against current and future variants,” said Dr. Sean Tucker, Vaxart’s SVP and Chief Scientific Officer. “We developed an Omicron specific vaccine candidate and compared it with our original Wuhan strain vaccine candidate that is currently in Phase II clinical trials. The study showed both vaccines could protect against Omicron challenge in a key preclinical model.”
The data reported today are from a study in which the S-only Wuhan and Omicron vaccine candidates were compared in a hamster challenge model.
- Animals were immunized mucosally on days zero and 28 and challenged on day 56 with an Omicron variant of SARS-CoV-2
- Both vaccines produced antibody responses to the S protein of Omicron, with the Omicron candidate slightly better at making serum IgG antibodies to the matched protein
- Weight loss, lung viral titers, and viral shedding were reduced in animals receiving either vaccine candidate compared to unvaccinated animals
These findings demonstrate that in this preclinical model both vaccine candidates protect against the Omicron variant.
Earlier this year, Vaxart announced that data from its non-human primate study showed that the S-only candidate generated antibodies to the original COVID-19 Wuhan strain and those antibodies also react strongly with the Beta, Delta, Alpha and Gamma variants of SARS-CoV-2 in the serum and nasal mucosa of non-human primates. In May 2021, the Company announced Phase I clinical test results demonstrating that its oral vaccine candidate, VXA-CoV2-1, which targets both the S and N proteins, produced broad cross-reactive T cell and IgA responses against other, non-COVID coronaviruses.
Vaxart continues to use pre-clinical and clinical data in conjunction with information on the evolution of the pandemic to make decisions on the COVID-19 vaccine candidates to move forward in its clinical development path.
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