It's probably fair to say that at the beginning of the year, many investors had never heard of VBI Vaccines (NASDAQ:VBIV) or Vaxart (NASDAQ:VXRT). But there's no doubt that a lot more investors know about these two companies now, as a result of their coronavirus vaccine efforts.

VBI Vaccines stock has more than doubled so far in 2020. Vaxart's shares have skyrocketed nearly 2,000%. Which of these two coronavirus-focused biotech stocks is the better pick for long-term investors?

A syringe labeled COVID-19 Vaccination

Image source: Getty Images.

The case for VBI Vaccines

In March, VBI Vaccines announced that it was collaborating with the National Research Council of Canada to develop a pan-coronavirus vaccine candidate. This vaccine would target not only COVID-19 but also two other members of the coronavirus family -- severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS).

This vaccine candidate is currently only in preclinical testing. VBI Vaccines has stated that "clinical study materials" are expected to be available for use in clinical studies in the fourth quarter of this year. However, it's uncertain when clinical trials will begin for the company's pan-coronavirus vaccine candidate.

VBI's lead pipeline candidate is hepatitis B vaccine Sci-B-Vac, which is already approved for sale in Israel. VBI hopes to start filing for regulatory approvals in other countries, including the U.S., in the fourth quarter of this year. If all goes well, Sci-B-Vac could become only the second hepatitis B vaccine approved by the Food and Drug Administration in more than 25 years.

The biotech also has a promising cancer vaccine in development. VBI expects to soon announce additional data from its phase 2a study evaluating VBI-1901 in treating glioblastoma multiforme, an aggressive type of brain cancer. It also anticipates reporting data from a study arm of the phase 2a trial with VBI-1901 and GlaxoSmithKline's AS01B adjuvant in the fourth quarter of 2020.

Perhaps the best argument for buying VBI Vaccines stock is that potential FDA approval for Sci-B-Vac should be a nice catalyst all by itself. Any positive developments from the biotech's pan-coronavirus vaccine or from VBI-1901 would be the icing on the cake.

The case for Vaxart

In January, Vaxart announced plans to develop an oral COVID-19 vaccine. The biotech reported positive preclinical data for this vaccine candidate in late April.

The big news for Vaxart, though, came just a couple of weeks ago. The U.S. government's Operation Warp Speed selected the company's COVID-19 vaccine candidate for funding and inclusion in a non-human primate challenge study. Vaxart's vaccine candidate was the only oral COVID-19 vaccine included.

Vaxart expects to initiate its own phase 1 study of its COVID-19 vaccine in the second half of 2020. The study could begin as early as this summer.

In the meantime, the company has several other pipeline candidates making progress. Vaxart hopes to soon announce results from preclinical testing being conducted, in collaboration with Johnson & Johnson, on its universal oral flu vaccine. Its oral norovirus vaccine performed well in a phase 1 study; Vaxart is seeking a partner to help advance that vaccine candidate.

Despite its meteoric rise so far this year, Vaxart's market cap still stands at around $600 million. Good news from the planned phase 1 study of its oral COVID-19 vaccine, or from the preclinical study funded by Operation Warp Speed, could provide another big boost for the biotech stock.

Better coronavirus stock

If we only evaluated these two stocks on their respective coronavirus programs, I'd say that Vaxart was the better pick. The company appears to be further ahead with its COVID-19 vaccine candidate than VBI Vaccines is with its pan-coronavirus vaccine candidate.

However, on an overall basis, I'd give the nod to VBI Vaccines. Unlike Vaxart, VBI already has an approved product (albeit only in one country for now), and it could win FDA approval for Sci-B-Vac next year. Vaxart has a much longer wait before it could have an approved product on the market.

But my bottom-line take is that it's too early for most investors to buy either one of these biotech stocks. There's still a lot that can go wrong. I think both Vaxart and VBI Vaccines are worthy of being on investors' radar screens. It's just too risky right now to call either one a great pick to buy.