While much of the discussion around COVID-19 vaccines has lately focused on the difficulties of shipping and storing them at temperatures that would make a polar bear shiver, Vaxart (VXRT -1.07%) has been steadily working on developing one that would eliminate a lot of the logistical complexity. The company's coronavirus vaccine candidate comes in tablet form, and is shelf-stable at room temperature.

Investors rewarded the effort by driving Vaxart's shares up by more than 1,500% last year, from $0.35 to $5.71. With gains like that in the rear-view mirror, could there still be upside for investors who buy shares today?

An elderly man wearing glasses and a flannel shirt reclining in a chair, holding a glass of water and a pill that he is about to ingest.

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A huge opportunity in oral vaccines

In June, Vaxart's COVID-19 candidate was tapped to be among those evaluated in a non-human primate study funded by Operation Warp Speed. It originally showed promise in animal studies; management expects that its phase 1 human clinical trials will be completed in the first quarter, and expects to launch phase 2 trials this quarter as well.

This isn't the company's first collaboration with the government on a vaccine. In mid-2019, Vaxart partnered with Johnson & Johnson's (JNJ -0.13%) Janssen unit to develop a flu vaccine in tablet form. That research was funded by the Biomedical Advanced Research and Development Authority (BARDA). The partners reported phase 2 study results in January 2020 that showed their oral vaccine at least matched the performance of Sanofi's influenza vaccine -- the market leader.

If Vaxart is successful, the potential for its valuation to soar is still enormous. The company only has a market cap of $715 million and is also working on vaccines for norovirus, human papillomavirus (HPV), and respiratory syncytial virus (RSV).

Even if one ignores the potential revenues for a norovirus vaccine (hard to gauge, because there are no currently licensed vaccines for it) and COVID-19 (because there are 50 candidates ahead of it in the clinical trial process), vaccines for those other conditions are expected to generate global annual sales of $21 billion by 2027. If Vaxart can win a share of that market, it will give shareholders plenty of reasons to stay excited about the stock in 2021 and beyond.