Europe is already beginning to reel from a second coronavirus wave. The U.K. recently posted its highest number of COVID-19 cases since May. Prime Minister Boris Johnson is implementing tighter restrictions that could be in effect for six months. Spain just put new restrictions in place in Madrid, the country's largest city.

What about the U.S.? Coronavirus cases are rising in 22 states. However, new cases are declining in several larger states, keeping the overall national numbers down. But epidemiology experts warn that the U.S. isn't out of the woods yet and that the pandemic could worsen in the fall. Johns Hopkins School of Medicine epidemiologist Eili Klein told The Washington Post earlier this month, "My feeling is that there is a [second] wave coming, and it's not so much whether it's coming but how big is it going to be."

Here are three stocks to buy before this grim reality hits.

Person in business attire looking at images of coronavirus and a world map with a city in the background.

Image source: Getty Images.

1. Abbott Laboratories

A second wave would almost certainly spur a major increase in the demand for COVID-19 diagnostic tests. That should translate to higher sales for Abbott Laboratories (ABT 0.19%).

Abbott markets six COVID-19 tests under the Food and Drug Administrations's emergency use authorization program. The company's BinaxNOW COVID-19 Ag Card antigen test could especially be a game changer. It's roughly the size of a credit card, highly accurate, generates results within 15 minutes, and costs only $5 per sample.

The company already won a $750 million contract with the U.S. government to supply 150 million portable COVID-19 antigen tests. That quantity might not be enough if the nation faces a second wave of the coronavirus outbreak.  

Even if the pandemic doesn't worsen, Abbott should still be a great stock to own. The company claims multiple growth drivers other than its COVID-19 tests, notably including its FreeStyle Libre 2 continuous glucose monitoring system. Abbott is also a Dividend Aristocrat with 48 consecutive years of dividend increases.

2. Pfizer

Many Americans eagerly await a safe and effective vaccine to protect against infection by the coronavirus that causes COVID-19. The clear leader in the coronavirus vaccine race is Pfizer (PFE -0.34%), according to Bill Gates -- and he's probably right.

Pfizer and its partner, BioNTech (BNTX -0.67%), expect to report initial results from late-stage testing of COVID-19 vaccine candidate BNT162b2 by the end of next month. Assuming those results show that the vaccine is safe and effective, look for the FDA to grant emergency use authorization as soon as possible.

The timing could be ideal for Pfizer investors if a second coronavirus wave hits this fall. Pfizer and BioNTech stand to rake in some big bucks right out of the gate no matter what happens, though. The companies signed a deal with the U.S. government to supply 100 million doses of BNT162b2 for $1.95 billion. That agreement also allows the U.S. to purchase another 500 million doses of the vaccine.

3. Teladoc Health

It's not just the stocks of COVID-19 tests and vaccines makers that would likely jump if a second wave comes. Teladoc Health (TDOC 1.20%) was a key beneficiary of the first coronavirus wave.

Many Americans tried using telehealth for the first time during this year's COVID-19 pandemic, and surveys found that most of them liked it. If coronavirus cases soar in the fall, so could the use of telehealth services. As the biggest virtual care services provider in the nation, Teladoc would undoubtedly experience a surge in demand.

I suspect that Livongo Health (LVGO) would also enjoy strong demand for its digital health platform, which targets chronic disease management, during a second coronavirus wave. That would be great news for Teladoc as well, since the two companies plan to merge. 

The Teladoc-Livongo transaction is expected to close before the end of this year. I think investors will appreciate the value of the merger a lot more if both companies see soaring sales in Q4, which is highly likely if the COVID-19 pandemic worsens in the U.S.