Earlier this year, Moderna (NASDAQ:MRNA) quickly emerged as a leader in the race to develop a coronavirus vaccine. The biotech's messenger RNA (mRNA) technology helped Moderna move faster than most companies in advancing a vaccine candidate into clinical tests in humans.

Today, Moderna stands as one of nine drugmakers with COVID-19 vaccine candidates in late-stage testing. The company is already more than six weeks into its phase 3 clinical trial of its vaccine candidate mRNA-1273. But Moderna revealed last week that it's slowing down enrollment in the study. Should investors be worried? No. Here's why.

Physician holding syringe to patient's arm.

Image source: Getty Images.

The reason for the slowdown

Moderna CEO Stephane Bancel stated in an interview with CNBC last week that the company is slowing enrollment in its phase 3 clinical trial evaluating mRNA-1273 to ensure minorities are represented sufficiently. This is important because the COVID-19 pandemic has disproportionately impacted the Black community.

As of Sept. 4, 2020, Moderna had enrolled 21,411 participants in the late-stage study of mRNA-1273 -- a little over 71% of the 30,000 participants targeted to be enrolled. Of those participants, 67% are white. Around 16% are Hispanic, and 10% of the enrolled participants are Black.

The U.S. Census Bureau estimates that 13.4% of Americans are Black. It also estimates that roughly 18.5% of Americans are Hispanic. Moderna hopes that its temporary enrollment slowdown will help boost its participant numbers to be more in line with these population percentages.

Bancel said in the CNBC interview, "We believe we could have one of the best vaccines." He added, "We want to ensure we have data for all the people who could benefit and be protected."

Why investors shouldn't worry

There are three key reasons why investors shouldn't worry about Moderna's enrollment slowdown. 

First, the delay in completing enrollment won't be a long one. Bancel told CNBC, "I would rather we have higher diverse [sic] participants and take one extra week." Even if the enrollment period extended a few weeks, it would still only be a relatively minor delay.

Second, Moderna's decision to focus on boosting the numbers of minority participants is a smart move over the long run. The last thing the company wants is to wrap up testing of mRNA-1273 only to have the Food and Drug Administration ask it to extend testing because of insufficient minority group representation. That kind of news might cause the biotech stock to plunge, whereas the announcement about the slight enrollment delay only resulted in Moderna's shares falling around 4% last week.

Third, which drugmaker makes it to the finish line in first, second, or third place simply won't matter all that much. Moderna already has a deal in place with the U.S. government to supply 100 million doses of mRNA-1273 for $1.525 billion. A small delay in participant enrollment for the vaccine's phase 3 study won't impact this agreement.

What's next for Moderna

When will Moderna complete enrollment in its late-stage study of mRNA-1273 or report initial results from the study? Bancel didn't give any details in his CNBC interview last week. However, he has previously stated that interim results could be available in October or November.

The good news for Moderna is that FDA Commissioner Stephen Hahn has stated publicly that COVID-19 vaccines could potentially receive fast-track emergency use authorization even before late-stage testing has completed. This means that Moderna's slight delay in wrapping up enrollment in its phase 3 study of mRNA-1273 shouldn't negatively impact its ability to get the vaccine to market quickly.

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.