What happened

Shares of Moderna (NASDAQ:MRNA) slipped 3.7% on Monday as of the market close. The decline appeared to be related to a report in The New York Times that said the U.S. Food and Drug Administration (FDA) requested that COVID-19 vaccine makers expand their clinical trials for children between the ages of five to 11 before seeking emergency use authorization (EUA).

So what

Although Moderna's shares fell on Monday, the delay in EUA filing for school-age children isn't all that bad for the company. The U.S. has already purchased more than enough COVID-19 vaccine doses to fully vaccinate all Americans this year, including younger children for whom the vaccines aren't yet authorized.

A medical professional administers a shot to a child wearing a protective face mask.

Image source: Getty Images.

The FDA didn't single out Moderna in its request for expanded clinical trials. It gave the same message to Pfizer (NYSE:PFE) and BioNTech (NASDAQ:BNTX), according to The New York Times report.

Both of these vaccine stocks rose slightly on Monday. The decline in Moderna's shares probably reflects the loftier valuation for the stock. Any hint of bad news is likely to affect Moderna's share price more than it would either Pfizer or BioNTech.

Now what

Moderna confirmed to multiple news organizations that it is "actively discussing a proposal with the FDA" about expanding its clinical trial in younger children. The company still expects to file for the expanded EUA in "winter 2021/early 2022." 

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