Vaxart (VXRT -10.73%) soared to stardom when its shares advanced 1,500% last year. Why the excitement?

The biotech company is developing a coronavirus-vaccine candidate in pill form. Investors realized such a product could win over those who cringe at the thought of needles.

But attention moved away from Vaxart after the first clinical-trial report. The candidate didn't produce neutralizing antibodies -- an element seen as key to blocking infection. Still, the investigational vaccine did boost immunity in other ways. And Vaxart continued along the development path.

Just recently, the biotech began recruiting for a phase 2 trial. With 56% of Americans fully vaccinated, though, your question now may: Will Vaxart be too late to carve out market share?

A person holds up a glass of water and a pill.

Image source: Getty Images.

The spike protein

First, a little bit about Vaxart's program. In phase 1, the company tested a candidate that targets two coronavirus proteins: the spike protein, which is used to infect, and the nucleocapsid, which is involved in the transcription of the virus into the body's cells. As mentioned above, this candidate didn't result in neutralizing antibody production.

For phase 2, the company selected a candidate targeting only the coronavirus spike protein. In non-human primate studies, this candidate resulted in higher antibody levels than the candidate targeting the two proteins.

Vaxart aims to recruit 96 volunteers in the U.S. Half of them will have been vaccinated by an mRNA vaccine, while the other half will be individuals who haven't been vaccinated or infected by the virus. Vaxart plans on expanding phase 2 to sites beyond the U.S. later in the year. It will launch the first of such sites in India.

In more positive news for the company, a recent study in hamsters showed its vaccine candidate reduces airborne transmission of coronavirus. This echoes results from Vaxart's phase 2 study of its investigational flu vaccine in humans. The flu candidate cut viral shedding more than an injectable flu vaccine.

All of this sounds promising.

Vaxart's market opportunity

Now let's look at Vaxart's market prospects. It's clear the company missed out on vaccinating during the pandemic. Moderna, Pfizer, and Johnson & Johnson shared that market.

Recently, former U.S. Food and Drug Administration (FDA) chief Dr. Scott Gottlieb told CNBC he expects the authorization of a coronavirus treatment pill and vaccines for kids to mark the transition from a pandemic into an endemic phase. Merck plans to request authorization of its treatment pill candidate soon. And Pfizer has requested authorization of its vaccine in kids ages five through 11. So a post-pandemic world may be only months away.

But that doesn't necessarily mean bad news for Vaxart or other latecomers. The coronavirus still will be around, so people still need protection. The situation may resemble that of the flu -- the virus will come and go in certain areas in an ongoing manner.

I expect countries to buy doses in advance each year. And it seems likely that individuals who go for an annual flu shot also will go for a coronavirus jab.

It's very possible a latecomer could carve out market share. But to do so, the company must have an innovative and efficacious candidate. Otherwise, countries likely will continue to order the vaccines they've already used and know well.

Vaxart is on the right track. As I said earlier, users will be happy to avoid a needle. But here's what's even more important: Healthcare facilities will find it easier to store a room-temperature-stable tablet than an injectable vaccine. (For example, the Moderna and Pfizer vaccines require cold temperatures.)

This makes the potential Vaxart product a practical option for use anywhere in the world. And it means Vaxart still may benefit from sales -- in spite of its potentially late arrival.

Should you buy Vaxart?

Does this mean you should buy Vaxart shares right now? It depends on your investment style. Vaxart doesn't have any commercialized products, but has six programs in the pipeline. And the most advanced is a seasonal flu vaccine candidate in phase 2 studies.

Clinical-stage companies always present a certain degree of risk. Anything can happen in clinical trials -- so there's no guarantee a product and revenue will be right around the corner. That's why it's best to invest in players like Vaxart only if you can accept this risk.

If you're a cautious investor, it's best to wait until Vaxart moves closer to the finish line with at least one candidate. If you're more aggressive, though, you may want to consider this company due to its game-changing technology.