With more than 39 million confirmed COVID-19 cases and upwards of 1.1 million deaths from the coronavirus worldwide, the pandemic continues to dominate attention. For investors who want to seek profits among companies fighting back against the coronavirus, there are a host of options -- some investigating potential treatments, others developing vaccines, still more providing diagnostic testing.

With so many coronavirus stocks to choose from, I recommend limiting your consideration to those with the strongest momentum. Two such companies are the biotechs Opko Health (OPK -4.28%) and BioNTech (BNTX -0.61%)

Medical worker testing for coronavirus at a drive-thru site.

Image Source: Getty Images.

The case for Opko Health

Opko is a diversified pharmaceutical company, and its contribution to the war on the coronavirus comes in the form of COVID-19 tests. To date, the company has conducted over 5.2 million coronavirus diagnostic tests and 331,600 COVID-19 antibody tests. This high demand has expanded Opko's bottom line significantly. During the second quarter, its revenue and net income grew to $301.2 million and $33.7 million, respectively, compared to Q2 2019's $226.4 million in sales and $59.8 million net loss.

The company also has a commercialized kidney medication, Rayaldee, which is eligible for over $899 million in milestone payments, as well as 10%-plus royalties from its distribution partners. Furthermore, its growth hormone replacement therapy, Somatrogon, demonstrated superiority against other drugs in its phase 3 clinical trials. The company is on track to submit a Biologic License Application for Somatrogon to the U.S. Food and Drug Administration (FDA) for approval by the end of the year. The estimated market opportunity for Somatrogon is upwards of $3 billion annually.

Opko stock would look surprisingly cheap even if it not for the coronavirus market opportunity, trading at a price-to-sales ratio of just 2.7. Since October 2019, Opko's share price is up by more than 100%.

The case for BioNTech

German immunotherapy specialist BioNTech (BNTX -0.61%) has what is arguably one of the most promising entries in the coronavirus vaccine race. That vaccine candidate, BNT162b2, which it is developing in partnership with Pfizer (PFE -1.82%), is currently well along in phase 3 clinical trials. So far, more than 28,000 out of 37,000 participants have received their second doses of the vaccine, and preliminary results from the study are expected by the end of October.

If BNT162b2 earns regulatory approval, Pfizer and BioNTech aim to manufacture 1.3 billion doses of the vaccine in 2021. At a price tag of $20 per dose, that translates to about $13 billion in potential revenue for BioNTech per its 50/50 partnership with Pfizer. That certainly sounds promising, considering that BioNTech only went public in October 2019 and has a market cap of just $22.3 billion.

Even before there is clarity on this vaccine candidate's efficacy, multiple governments worldwide have already lined up to place orders for it. The company has inked deals to supply the U.S., U.K., and Japan with 600 million, 30 million, and 120 million doses of BNT162b2, respectively, and is in talks with the E.U. to sell the supranational entity 300 million doses.

Over the past year, BioNTech stock is up by a stunning 600%.  

Which stock is the better buy?

The pandemic is likely to wind up being a one-time tailwind for these healthcare sector players.

In the case of BioNTech, the company could potentially generate billions of dollars of revenue in the first two years of BNT162b2's commercialization, but after that, it's likely to see sales of that vaccine dwindle as populations largely become immunized against SARS-CoV-2 and the threat fades. In fact, the top vaccine players already have the production capacity to vaccinate at least half of the world's population by 2022. 

Demand for Opko's COVID-19 diagnostic and antibody tests is also likely to decline significantly as coronavirus vaccines begin to be widely administered. Still, Opko is the better buy here, with a more robust pipeline and product mix beyond its coronavirus-related offerings.