What happened

Shares of Moderna (MRNA 3.28%) were climbing 3.7% higher as of 11:45 a.m. EDT on Thursday. The gain appears to reflect a sigh of relief among investors after the U.S. Food and Drug Administration (FDA) stated that it would add a warning to the label of Moderna's COVID-19 vaccine about the potential for adolescents and young adults to experience rare heart inflammation issues. This FDA warning isn't likely to impact Moderna financially.

So what

A Centers for Disease Control and Prevention (CDC) advisory committee met on Wednesday to review data related to a potential link between messenger RNA vaccines and heart inflammation cases. Investors seemed to fret somewhat about how potential actions taken by the CDC and FDA in response might affect Moderna, with the biotech stock falling more than 4%.

Doctor giving a shot to a person with a healthcare professional watching.

Image source: Getty Images.

However, any such worries were overblown. There's no reason to expect that the new label warning will change the prospects for Moderna to win additional supply deals for its vaccine.

Now what

The main thing to watch with Moderna now is how the emergence of new coronavirus variants could impact the COVID-19 vaccine market. It's quite possible that the spread of the more contagious Delta variant could work in the company's favor as governments see an increased possibility of administering booster doses in the near future.