Pfizer (NYSE:PFE) and Moderna (NASDAQ:MRNA) have been marching in lockstep for nearly a year. They both announced the start of phase 3 trials for their coronavirus vaccine candidates on the same day last July. Pfizer won Emergency Use Authorization for its vaccine only about a week ahead of Moderna. And the U.S. ordered 300 million doses from each company earlier in the year. That was enough to vaccinate almost the entire population.

It's fair to say both of these companies today are leading the coronavirus vaccine market. Still, Pfizer has inched ahead in a couple of ways. It has fully vaccinated more Americans than Moderna so far. And recently, it scored an order for as many as 1.8 billion doses from the European Union through 2023. That's in addition to an earlier order. But that's not all. There are three other areas where Pfizer is beating Moderna...

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1. The path to full approval

Pfizer and partner BioNTech said last week the U.S. Food and Drug Administration granted their vaccine priority review. The agency's standard review time usually takes between six to 10 months. Priority review takes a maximum of six. So, in this case, the agency's deadline to make an approval decision is in January. In even better news, an FDA official told CNN that regulators may issue a decision in as little as two months.

Where does Moderna stand? The biotech submitted its request for approval a month behind Pfizer. Moderna also requested priority review. If all goes smoothly for Moderna, it may follow in Pfizer's footsteps. And in this case, we might expect a regulatory decision about a month after the Pfizer decision. If any issues arise, of course, Moderna could fall behind.

2. The booster plan

Pfizer and Moderna announced work on boosters to address variants earlier this year. Both companies are studying variant-specific candidates as well as an extra dose of their vaccines. But Pfizer made the study of a third vaccine dose the priority. And the company recently said it will ask for regulatory authorization of that dose in the coming weeks. Meanwhile, it plans to begin clinical trials of a variant-specific version of its vaccine in August.

Moderna simultaneously started clinical trials of three candidates: an extra dose of vaccine, a strain-specific candidate, and a combination of its vaccine and the strain-specific candidate. The company has said it will have a booster ready by fall.

If Pfizer stays on track, it looks like it will make it to market ahead of Moderna though. Pfizer's data are ready for regulators -- and it may be easier to win authorization for another dose of a vaccine that's already been given to millions of people than a new candidate.

3. Back-to-school vaccinations

Regulators in the U.S. and Europe authorized Pfizer's vaccine in teens 12 through 15 back in May. The original authorization includes individuals ages 16 and older. The company reported positive trial data on March 31.

Moderna announced positive results from its teen study in late May -- and the company applied for authorization in the U.S. and Europe about two weeks later. Regulatory decisions may come any day now. But Pfizer has a clear advantage. Its vaccine got the OK before teens headed off to summer activities or vacation. And that's likely when a lot of teens would opt for vaccination to be fully protected before school starts. Pfizer and Moderna vaccines require two doses about a month apart.

What does all of this mean for investors?

These points are good news for Pfizer. A fully approved vaccine likely will attract many individuals who hesitated to go for an experimental product. So, if the FDA gives a nod, more and more people may request a Pfizer jab. A quicker-to-market booster and an authorization for teens also mean more individuals may go for a Pfizer shot in the near term.

But none of these points will immediately equal more revenue for Pfizer. Governments already have purchased doses. If Pfizer stays ahead of Moderna on each of the above points, though, these doses may be used up faster than planned. And that may mean more orders down the road. And therefore, more revenue. The first-to-market status also may keep governments coming back for more of the same -- so Pfizer may attract bigger orders.

All is not lost for Moderna though. Far from it. Yes, Pfizer is dominating in the above areas. And that may even continue. But Moderna isn't far behind. As we've seen so far, there's room for more than one player in this market. Pfizer expects $26 billion in vaccine revenue this year. And Moderna's advance purchase orders total $19.2 billion so far. Both already are winning orders for 2022.

This means an investment in either of these coronavirus vaccine leaders today is likely to pay off now -- and in the long term.

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.