No company has yet launched a booster that targets the coronavirus omicron variant. However, Pfizer (PFE 2.40%) and its German partner BioNTech (BNTX 0.74%) are scrambling to do so. So is their top rival, Moderna (MRNA -0.58%).

There's a significant U.S. market for omicron boosters even before the new vaccines are available. And there's already an early winner. Pfizer and BioNTech appear to be beating Moderna in this market -- at least, so far. 

Winning on two fronts

The U.S. government has finalized supply agreements with Pfizer-BioNTech and Moderna that include the companies' respective omicron boosters. Both deals are for up to 300 million doses. However, there are a couple of important details in the supply agreements that give Pfizer and BioNTech key advantages.

First, Pfizer and BioNTech received a much larger initial order than Moderna. The U.S. is buying 105 million doses of the Pfizer-BioNTech vaccine for delivery through the fourth quarter of this year. Moderna's initial order is for 66 million doses.

To be sure, the U.S. deal with Pfizer and BioNTech stipulates that it "may include adult Omicron-adapted COVID-19 vaccines," while Moderna's deal is specifically for its bivalent booster that targets both the original coronavirus strain as well as omicron. However, it seems likely that the U.S. will primarily order the Pfizer-BioNTech omicron boosters rather than the current version of the companies' COVID-19 vaccine. Pfizer CEO Albert Bourla stated in the company's Q2 call that Pfizer is targeting a fall rollout of its omicron booster, pending regulatory authorization.

Second, Pfizer and BioNTech are commanding a premium for their vaccine. The U.S. is spending $3.2 billion to purchase the initial 105 million doses. That's an average price of $30.48 per dose. Meanwhile, Moderna will receive "up to $1.74 billion" for the initial 66 million doses. The average price per dose is $26.36.

Behind the early lead

Why were Pfizer's and BioNTech's terms more favorable than Moderna's? It's probably due to the demand seen so far for the different COVID-19 vaccines.

More than 356.7 million doses of the Pfizer-BioNTech vaccine have been administered. Moderna comes in a distant second, with around 227.5 million doses administered as of July 27.

Pfizer and BioNTech are well ahead of Moderna based on first boosters received also. While Moderna pulled much closer on the second booster counts, Pfizer and BioNTech are still in the lead with a little over 11 million doses, compared to slightly above 10 million doses for Moderna's booster.

A couple of other factors could also be at play. Moderna received significant U.S. federal funding to help the company develop its initial COVID-19 vaccine, whereas Pfizer and BioNTech didn't. Also, the Biden administration seems to have had a less adversarial relationship with Pfizer than it's had with Moderna (mainly related to pressure for Moderna to supply more vaccines for low- and middle-income countries).

Where Moderna prevails

Moderna is prevailing in some ways over Pfizer and BioNTech, though. For example, the vaccine stock has soared more in recent weeks than its rivals' shares have.

One explanation behind this outperformance is that Moderna benefited more from its new U.S. supply deal than either Pfizer or BioNTech did with their agreement. Moderna gets to pocket all of its COVID-19 vaccine revenue, but Pfizer and BioNTech split their profits equally.

Perhaps Moderna's omicron booster will ultimately enjoy higher demand than the competition. Even if not, though, Moderna could still emerge as the biggest winner because of the company's full rights to its vaccines.