The first jab of Moderna's (NASDAQ:MRNA) two-shot coronavirus vaccine hasn't made it into the arms of the millions who will eventually receive it, but the company is already planning to gauge the effectiveness of a booster.

In a presentation at this year's annual J.P. Morgan Healthcare Conference, Moderna said it plans to do so in a clinical trial involving participants of earlier studies of the vaccine, mRNA-1273. It has already begun contacting potential participants, and it plans to begin the study in July.

A patient receiving a vaccination shot.

Image source: Getty Images.

"From what we've seen so far, I think our expectation is that the vaccination should last you at least a year," Moderna Chief Medical Officer Tal Zaks said during the conference. "To the degree that you need a booster shot, we'll make a data-based recommendation, and that will require us getting the data."

In the planned study, Moderna will try to determine the level of immune response still being generated by the booster shot, CEO Stephane Bancel said at the event.

The timing is right for a follow-up study, as the participants in the first clinical trials of the vaccine are nearing their one-year anniversary of receiving the booster. They were given the first shot in the middle of March 2020.

Moderna is one of two coronavirus vaccines that have been granted emergency use authorization by the U.S. Food and Drug Administration. However, the rollouts of mRNA-1273 and Pfizer/BioNTech's similarly two-shot BNT162b2 have been slow. The numbers of patients who have received the first dose remain worryingly low.

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.