Come up with a pill that could end the worst health crisis in over a century, and you might find investors scrambling to buy your company's stock. That's exactly what's been going on with small-cap biotech stock Vaxart (VXRT -4.29%), and investors who owned the stock at the beginning of the year have seen their investment explode by a factor of 50.

Vaxart announced on Jan. 31 that it was working on a vaccine pill for the novel coronavirus that had recently been reported in Wuhan, China. That was good for a 71% pop in the stock price to $1.25, but the big gains came starting June 25, when the company announced it had signed a manufacturing deal with Attwill Medical Solutions Sterilflow, LP to crank out a billion doses of its COVID-19 vaccine pill. The next day, the company said its vaccine candidate had been selected for a non-human primate challenge study by Operation Warp Speed, and all of a sudden the market saw it as a serious contender in the COVID-19 vaccine race, with shares peaking at $17.49 on July 14.

Hand positioning blocks with percent signs of rising graph.

Image source: Getty Images.

Beside the advantages of the pill form, the clinical-stage biotech says its vaccine produces a type of antibody (IgA) that's secreted in mucosal cells, potentially providing extra protection against airborne transmission and differentiating it further from the competition.

Vaxart just took the first step toward human clinical trials on Aug. 10. The company has a long way to go to prove the vaccine actually works, and there's evidence that the IgA antibody to SARS-CoV-2 is short-lived, but investors willing to take a chance on the stock and who missed the big run can buy the shares for 47% less than July's peak.