As the world holds its breath in hopes of vaccines, tests, or therapies to mitigate the impact of COVID-19, coronavirus stocks are among the hottest on the market. Between a barrage of breakthroughs in vaccine clinical trials and nonstop innovation in the coronavirus diagnostic market, healthcare companies are under intense scrutiny from investors. And with a glut of government funding sloshing into companies' research and development budgets, there are plenty of new product initiatives to keep track of.

Unfortunately, now is also a time of immense speculation in the market. In many cases, the prospect that a company might make a coronavirus vaccine has turned its stock into a lottery ticket. Meanwhile, established companies with proven track records in product development may not be getting the appreciation from the market that they deserve as they create new and lucrative solutions to some of the pandemic's thorniest problems. Let's take a closer look at a pair of companies that you're probably already familiar with to see what makes them worth buying right now.

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AstraZeneca

AstraZeneca (NASDAQ:AZN) is well-known as a successful pharmaceutical company with a roster of profitable drugs and deep experience in the clinical trial process. So, when management announced that it was working on a coronavirus vaccine candidate earlier this year, the market responded favorably -- at least until the company's clinical trial hit a roadblock recently.

As a result of unexplained side effects experienced by one of the patients enrolled in AstraZeneca's coronavirus vaccine trial, the company was forced to halt its U.S. clinical investigations. And, with the U.S. Food and Drug Administration (FDA) announcing Oct. 2 that its regulatory inquiry into these side effects would need to expand rather than conclude, it looks like AstraZeneca's trial will remain on hold for even longer. 

How could this seemingly expanding obstacle possibly make AstraZeneca a coronavirus stock that's worth buying now? For one, the market will likely overreact to the significance of the clinical hold. Clinical holds happen all the time during drug and vaccine development, including with many therapies that go on to receive regulatory approval after they successfully finish clinical trials, and AstraZeneca has already resumed its vaccine trials in the U.K.

This is also a company that will experience long-term growth regardless of the fate of its coronavirus vaccine candidate. The candidate is only one tiny portion of the company's massive development pipeline, and given how many in-demand therapies it's developing, this might not even be the most profitable project in the works.

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Abbott Laboratories

Abbott Laboratories (NYSE:ABT), meanwhile, is a top coronavirus stock thanks to its efforts in the diagnostic testing market. While Abbott does develop plenty of therapeutic drugs, its tests are what makes it worth buying right now. Abbott has products in every segment of the testing market, including rapid tests, multiplexable diagnostic tests, and antibody tests.

Between its first coronavirus testing products like the ID NOW rapid diagnostic system and more recent innovations like the $5 BinaxNOW rapid antigen test, Abbott has been an industry leader, and it shows no signs of stopping. In the second quarter of this year alone, the company sold more than 40 million COVID-19 tests worldwide.

It's highly likely that Abbott will continue to iterate on its successful tests to develop new products that cater to the needs of consumers and healthcare providers alike -- for example, rapid saliva-based tests that can be administered without a clinician. That rising revenue will bring shareholders growth, but coronavirus-related gains won't be the only factor driving returns. Abbott's newest glucose monitoring device exhibited sales growth of 40% last quarter, and the company also received the green light to commercialize the newest member of its family of implantable cardiac defibrillators.

With new revenue sources constantly cropping up as a result of Abbott's herculean product-development pipeline, the company's coronavirus testing efforts are only the latest bit of icing on the cake for investors.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.