Vaxart (NASDAQ:VXRT) has seemingly fallen further behind in the coronavirus vaccine race. On Monday, the company unveiled preliminary data from a phase 1 study of its vaccine candidate, VXA-CoV2-1, that showed a potentially significant weakness.

The company reported that its oral tablet vaccine candidate was generally well-tolerated. The data also indicate that it was able to produce an immune response to coronavirus antigens. No severe adverse events were recorded, and those adverse events that did occur were generally mild. 

A coronavirus colony.

Image source: Getty Images.

The discouraging news is that neutralizing antibodies specific to the coronavirus were not detected in the participants who took a single dose of the vaccine. They were, however, found in nasal swab samples of people who received two doses. These types of antibodies are key parts of the immune system's defense against invaders.

The study's 495 participants were divided into three groups. One of these received a single low dose of VXA-CoV2-1. The second received a single high dose. The third cohort was administered two low doses, 29 days apart.

Vaxart CEO Andrei Floroiu waxed enthusiastic about the findings. "These results, together with recent data from our peers, further raise our confidence in the success of VXA-CoV2-1 and the broad potential of our platform," he said.

Yet they were seen as disappointing by investors, almost certainly because of that lack of neutralizing antibodies in the one-dose recipients. Clinical testing demonstrated that the two vaccines currently authorized for emergency use in the U.S., Moderna's (NASDAQ:MRNA) mRNA-1273 and Pfizer (NYSE:PFE) and BioNTech's (NASDAQ:BNTX) BNT162b2, both induce such antibodies.

Hopes have been high for Vaxart's coronavirus vaccine candidate because it is a tablet. As such, it does not have the demanding temperature storage requirements of the Moderna and Pfizer/BioNTech injectable vaccines (among others being developed). So if it earns regulatory approval, it could be transported and administered far more easily, and offer access to a vaccine in parts of the world where cold-chain shipping infrastructure is limited or unavailable.

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