What happened

Shares of Moderna (MRNA -1.11%) were falling 3.3% as of 3:34 p.m. EDT on Friday. The decline came after The Wall Street Journal reported that the U.S. Food and Drug Administration is delaying a decision on Emergency Use Authorization for Moderna's COVID-19 vaccine in adolescents ages 12 through 17.

So what

The FDA's delay is related to potential concerns that Moderna's vaccine could increase the risks of heart inflammation in rare cases among younger individuals. Several Nordic countries have halted the use of the vaccine in young age groups, especially young men, due to this issue.

A person receiving a shot in the arm.

Image source: Getty Images.

A later decision won't really affect Moderna from a financial standpoint over the near term. The U.S. has already ordered 500 million doses of the company's COVID-19 vaccine. That's more than enough to vaccinate all Americans along with the government's supply deals with other vaccine makers.

What if the U.S. opts to limit Moderna's vaccine from being administered to adolescents? It could impact Moderna's vaccine sales over the long term.

Today's decline for the vaccine stock was offset to some extent by good news. An FDA advisory committee voted unanimously to recommend EUA for a booster dose of Moderna's vaccine in individuals ages 65 and older and for individuals at high risk of developing severe COVID-19. 

Now what

The Wall Street Journal stated that the FDA could delay its decision by several weeks but didn't have details on the timing. It remains to be seen what, if any, impact the concerns about the rare heart inflammation issues will have on Moderna's ability to secure additional supply deals going forward.