COVID-19 hasn't gone away. But a quick look at the charts of Pfizer (PFE 1.53%) and Moderna (MRNA 7.13%) stocks will tell you that the coronavirus isn't as big of a concern as it used to be.

The situation could change in the near future, though. Some scientists believe the evidence is pointing to the likelihood of yet another COVID-19 wave in the fall and winter. In particular, they're tracking new coronavirus variants. Are Pfizer and Moderna stocks buys right now with a potential COVID-19 surge on the way?

Two key questions

We must address two key questions to get a feel for how these vaccine stocks are likely to perform going into 2023. First, how bad might the next coronavirus outbreak be? Second, how much impact might another COVID-19 wave have on vaccine sales for Pfizer and Moderna? Unfortunately, no one knows for sure what the answer is to either question.

It's not a foregone conclusion that the U.S. is in store for a major COVID-19 wave in the fall and winter. In August, the COVID-19 Scenario Modeling Hub predicted several potential scenarios. There is a realistic scenario where the country could experience a relatively mild coronavirus season. 

This optimistic scenario hinged in part on no new coronavirus variants emerging. But multiple new omicron sub-variants are already showing up in some European countries. Evolutionary biologist Tom Wenseleers told Nature magazine recently that he's "fairly confident that at least one of these variants or a combination of them will lead to a new infection wave."

Even if there's a serious COVID-19 surge over the next few months, Pfizer and Moderna won't necessarily benefit from increased vaccine sales. So far, the U.S. has ordered 105 million doses of the omicron-targeting booster developed by Pfizer and BioNTech. Around 41.4 million doses have been delivered but only 12.4 million doses have been administered. The U.S. ordered 66 million doses of Moderna's omicron booster. Nearly 18.4 million of those doses have been delivered with fewer than 7 million doses administered.

Different dynamics

It's also important to understand that there are different dynamics at play for Pfizer than there are for Moderna. Pfizer's shares have tumbled more than 20% year to date, roughly in line with the S&P 500's decline.

While Pfizer makes a lot of money from its COVID-19 vaccine, it has other sources of revenue. For example, oral antiviral therapy Paxlovid is already on track to rake in around $22 billion this year. A severe COVID-19 surge could boost sales of the drug, although states will have some doses stockpiled headed into winter.

On the other hand, Moderna is entirely dependent on sales of its COVID-19 vaccine at this point. That explains why the stock has plunged close to 50% this year as concerns about the pandemic faded.

The near-term performances for both of these stocks hinge largely on what happens next with COVID-19. Over the longer term, it could be a different story. Pfizer has several other drugs with strong sales growth already on the market plus a broad pipeline. Moderna has promising late-stage vaccine candidates targeting flu, cytomegalovirus (CMV), and respiratory syncytial virus (RSV). 

The best answer

So are Pfizer and Moderna stocks good picks to buy now in anticipation of a coming COVID-19 surge? Perhaps the best answer is the one that few will like: It depends. In particular, the answer to the question depends on how much risk you're willing to take on and how long your investing time horizon is.

There is considerable uncertainty for both Pfizer and Moderna over the next couple of years. I'm not entirely convinced that a coronavirus wave in the fall and winter will serve as a huge catalyst for either stock.

However, Pfizer looks like a good choice in my view for income investors with its dividend yield of nearly 3.6%. The company's long-term growth outlook is improving with its acquisitions.

I think anyone looking for relatively quick profits should be leery of betting on Moderna. But one of the things that the smartest investors know about the stock is that its future prospects go far beyond COVID-19. If your investing horizon is 10 years or longer and you don't mind a lot of risk and volatility, Moderna could be worthy of consideration.