Moderna (NASDAQ:MRNA) beat Novavax (NASDAQ:NVAX) to market with a coronavirus vaccine. The U.S. Food and Drug Administration (FDA) authorized Moderna's candidate in December. Novavax expects to report U.S. phase 3 trial data in the coming weeks and complete an Emergency Use Authorization (EUA) request this quarter.

But Novavax has a particular strength that makes it stand out in the sea of coronavirus vaccine developers. The company has an investigational flu vaccine that is only a step away from commercialization. And Novavax eventually aims to combine this candidate -- NanoFlu -- with its coronavirus vaccine candidate. Last week, though, Moderna's CEO Stephane Bancel said something that may jeopardize Novavax's chance to shine.

A doctor's gloved hands draw up coronavirus vaccine in a syringe.

Image source: Getty Images.

The flu vaccine business

Moderna last fall announced plans to enter the flu vaccine business. Then, early this year, the biotech company said it would test various combination flu vaccines. They would potentially include respiratory viruses such as the coronavirus, respiratory syncytial virus, and human metapneumovirus.

Now, Moderna's intentions to pursue a combined flu/coronavirus vaccine -- and soon -- seem clear after a conversation Bancel had with CNBC.

"What we're trying to do at Moderna actually is to get a flu vaccine in the clinic this year and then combine our flu vaccine to our Covid vaccine so you only have to get one boost at your local CVS store... every year that would protect you to the variant of concern against Covid and the seasonal flu strain," Bancel told CNBC.

Moderna plans to start phase 1 trials of flu vaccine candidates this year.

Now, the questions are: How quickly can Moderna bring a combined product to market? And could it get there before Novavax?

So far, Moderna's timelines have been particularly short due to the urgent need for a coronavirus vaccine. It brought its vaccine to market in about nine months. It started development of a booster shot to target strains of concern in January. And it plans to launch the booster this fall, Bancel said in the CNBC interview.

Once health authorities declare the pandemic over, however, regulators may be less likely to offer EUAs. And timelines may lengthen. That means a combined flu/coronavirus shot may be a few years away.

The next step

Novavax's NanoFlu last year met all primary endpoints in a pivotal trial. The next step is a regulatory request. And, as I mentioned earlier, Novavax's coronavirus candidate also is nearly ready for a regulatory request if the upcoming trial report is positive.

But the company still must test a combined coronavirus/flu candidate in clinical trials. And it's not clear when that may happen. Novavax in October said it was exploring the possibility of a combined vaccine. The company reiterated this plan in its earnings report last month.

Here's Novavax's advantage: The company's investigational flu and coronavirus vaccines are close to commercialization. Moderna is only at the start of its flu vaccine journey.

But here's the Moderna advantage: Moderna's mRNA technology allows it to produce a vaccine candidate quickly. Researchers don't have to go through the traditional time-consuming steps of growing virus and purifying viral proteins. Once researchers have a virus' genetic code, they can produce a vaccine candidate within a few days. So, Moderna may rapidly produce combined flu/coronavirus vaccine candidates.

What does all of this mean for Novavax?

Moderna's plan to work on a combined vaccine could mean bad news for Novavax -- if Novavax lags too far behind. If Moderna enters the market first and remains the only one with a combined vaccine for a while, it could establish itself as a leader. And that would make it more difficult for Novavax to carve out market share later. So, it's important for Novavax to move forward with a combined flu/coronavirus vaccine candidate -- and enter the market first or at least close behind Moderna.

Of course, it's still too early to predict which company may commercialize a combined vaccine first. And here's some good news for both Moderna and Novavax. As we've seen with current coronavirus vaccinations, there's room for more than one player in the market. So even a late entry could lead to revenue growth for both of these biotech companies.

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.