It's no secret that we need several companies' products to gain approval in order to meet worldwide demand for a coronavirus vaccine. Pfizer (NYSE:PFE) and Moderna (NASDAQ:MRNA) reached commercialization first when the U.S. Food and Drug Administration (FDA) granted their vaccine candidates Emergency Use Authorization (EUA) late last year. Johnson & Johnson (NYSE:JNJ), AstraZeneca (NASDAQ:AZN), and Novavax (NASDAQ:NVAX) are close behind. If each produced vaccines at top capacity, we still wouldn't have enough supply to immunize everyone worldwide. So, globally, there is plenty of business for all.

But how about if we look at only the U.S.? Here, the story is different. And it means fewer vaccine makers may prevail -- especially after President Joe Biden's latest move. The government is trying to buy enough vaccines for nearly every American -- from Pfizer and Moderna. And that means these early players may be about to take hold of the entire U.S. market. Let's take a look at what that means for Pfizer and Moderna today and down the road.

COVID-19 vaccine is drawn up in front of an American flag.

Image source: Getty Images.

Increasing total orders

The U.S. government is seeking to increase its total order of doses from both companies from 400 million to 600 million. The U.S. population totals about 330 million. And the Pfizer and Moderna vaccines involve two doses. So, if every person wanted a vaccine, we would need 660 million doses. If the Biden administration succeeds in increasing its order for Pfizer and Moderna vaccines, that leaves little room for another player to sell a rival vaccine.

For Pfizer and Moderna, of course, this is excellent news. We can estimate revenue by using the figure the U.S. government paid earlier for doses. That's $19.50 a dose for Pfizer's vaccine and $15 for Moderna's. The government already has ordered 200 million doses of each vaccine and now is aiming to buy another 100 million from each company. The total represents $5.8 billion in revenue for Pfizer and $4.5 billion for Moderna.

Of course, both companies now have to show they can deliver. Moderna expects to produce 200 million doses for the U.S. by the end of June. Pfizer and its partner BioNTech (NASDAQ:BNTX) have said they will supply the U.S. with that number of doses by the end of July.

Success here would secure both companies' positions as top coronavirus vaccine providers for the U.S.

But for how long? At least during this year and likely into 2022. And Moderna might have two more advantages on the horizon. The biotech company is testing its coronavirus vaccine in teens ages 12 through 17. If all goes well in this phase 2/3 trial, the company hopes to win an EUA in time for the fall back-to-school period. Moderna also is investigating a booster shot specifically targeting the South African coronavirus variant. That's the strain considered most likely to evade the efficacy of current drugs and vaccines.

What about the future?

But what happens to Pfizer and Moderna's U.S. market leadership in the future? That will depend somewhat on how the companies manage new strains -- and the logistics of delivering their vaccines. It also will depend on something they can't control: the competition.

If rivals bring more efficacious or easier-to-use vaccines to market, Pfizer and Moderna may lose market share. For instance, Johnson & Johnson is studying a one-dose vaccine in phase 3 trials. And smaller player Vaxart (NASDAQ:VXRT) is working on a vaccine in the form of a shelf-stable oral tablet. These features eventually could give them an edge.

But let's return to the present. Right now, Pfizer and Moderna are about to capture the entire U.S. market -- and make billions of dollars. With their first-to-market advantage, they're each likely to hold onto a portion of the worldwide market as well. So, even if they eventually lose some of the U.S. market down the road, their overall position should remain strong.

Right now, President Biden's policy represents opportunity for Pfizer and Moderna. They're steps ahead of pharmaceutical and biotech rivals, and those rivals will have to show their vaccines are more efficacious or far easier to distribute in order to steal the lead.

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.