What happened 

Shares of Moderna (MRNA 0.89%) climbed 7.5% on Tuesday after health officials in the U.K. approved the drugmaker's COVID-19 vaccine for children ages 12 to 17. 

So what

The Medicines and Healthcare products Regulatory Agency (MHRA) issued a conditional approval for Moderna's vaccine, now called Spikevax, based on clinical trials that showed the drug to be safe and effective in kids 12 years of age and older. 

A healthcare professional is administering a vaccine to a teenager.

Image source: Getty Images.

The news comes as COVID-19 case counts are rising at an alarming clip in many areas of the world, driven by the spread of the highly contagious Delta variant. Health officials hope the vaccine will help to reduce the spread of the disease when students return to school in the coming weeks.

Now what

Additionally, U.S. health regulators are reportedly planning to authorize booster shots for most Americans. The move would allow people who received two doses of Moderna's or Pfizer's coronavirus vaccines to receive a third dose, thereby boosting their ability to fend off the virus. The Biden administration could make the announcement as soon as this week, according to The New York Times

A third round of doses would likely also help to boost Moderna's sales and profits. Investors know this, and they responded to the news by bidding up the vaccine maker's stock price today.