Things were looking gloomy for Vaxart (VXRT -6.00%) a few months ago. The clinical-stage biotech company reported that its COVID-19 vaccine candidate didn't produce neutralizing antibodies in a phase 1 trial. These antibodies are considered key since their role is to fight infection. As a result, Vaxart's shares tumbled 58% in one trading session.

But all is not lost. This week, the company shared details of its studies and its development plans. Vaxart's investigational vaccine works in a different manner than those of market leaders Pfizer (PFE -0.97%) and Moderna (MRNA 0.17%). And it may even offer some advantages. Let's look at three of them.

A young woman takes a pill with a glass of water.

Image source: Getty Images.

1. It's a pill

Here's why Vaxart has intrigued investors from the start. The company is developing an oral coronavirus vaccine. It's a tablet to be taken with a glass of water -- as simple as taking a common pain reliever.

It's clear that if such a candidate is successful, it could win over many individuals -- even some who have refused vaccination so far. A Quadrant Strategies poll commissioned by Vaxart confirmed that: About a third of those who refuse vaccination would give it a go if they could choose a pill, the poll showed.

A pill also would be a game-changer for countries and healthcare systems. It's stable at room temperature so it doesn't require refrigerated transport or storage. This makes it easier to deliver and stock the vaccine anywhere in the world.

2. Higher T cell responses

The Pfizer and Moderna vaccines stimulate the body to produce neutralizing antibodies against the coronavirus' spike protein. The spike is used to infect. These antibodies later will protect the vaccinated individual in case of contact with the virus.

Vaxart's candidate doesn't work this way. Instead, it results in strong production of killer T cells. These cells don't completely prevent infection, but they can quickly remove virus from the body. That's because their role is to kill infected cells. And here, Vaxart may have an edge over the market leaders.

Vaxart studied T cell responses in nine volunteers vaccinated with the Pfizer or Moderna vaccines. It found the responses were lower than those produced by its investigational vaccine in the phase 1 trial. Scientists say T cells may play an important role in coronavirus immunity. For example, studies have detected T cells reactive to severe acute respiratory syndrome in former patients 17 years post-infection.

So there is evidence T cells could provide lasting immunity. Of course, Vaxart's later-stage trials must confirm the ability of these cells to quickly clear infection, before illness takes hold.

3. Targeting strains

The Pfizer and Moderna vaccines have demonstrated ability to handle new strains so far. That's because mutations to the spike protein have been limited. But if mutations increase, effectiveness could decrease. Both companies are working on boosters to handle the potential problem.

Vaxart may not have to worry about new strains. Its candidate doesn't target the spike protein only. Instead, it targets both the spike protein and the nucleocapsid, or "N" protein -- that protein is involved in viral replication. Targeting both broadens the vaccine's ability to protect, especially if the spike mutates.

"The strength of T-cell responses against both S and N proteins, which we targeted, leads us to believe that VXA-CoV2-1 offers a promising solution to variants," said Dr. Sean Tucker, Vaxart chief scientific officer.

Now what's the plan?

Vaxart aims to advance its coronavirus vaccine candidate into a phase 2 trial by the middle of this year. The company also will test two candidates targeting the spike protein only and focusing on specific variants. Those will enter phase 1/2 studies in the third quarter. And Vaxart also plans on testing its candidates as boosters in individuals who already have been vaccinated with an authorized vaccine. That should happen in the second half.

If one of Vaxart's candidates is successful, the biotech company clearly will be a latecomer to the coronavirus vaccine market. That means it has to stand out if it hopes to gain market share. The advantages highlighted above show Vaxart may have what it takes to carve out a spot in this competitive market in the future.

Still, risk is high -- at least until we see efficacy data from the phase 2 trial or the booster trials. Vaxart's potential product works differently than more-advanced rivals. So we can't look to others for clues about whether its candidate might work. All of this means Vaxart is definitely a stock to watch, but only the most aggressive investors should consider buying it right now.