What happened

Shares of Moderna (MRNA -1.02%) climbed 5% on Friday after U.S. health regulators took steps toward making COVID-19 booster vaccines available for more Americans. 

So what

The U.S. Food and Drug Administration (FDA) authorized booster shots developed by Moderna and rival drugmaker Pfizer for people aged 18 and older. The shots are designed to be administered at least six months after people receive their second dose.

"Throughout the course of the COVID-19 pandemic, the FDA has worked to make timely public health decisions as the pandemic evolves," acting FDA commissioner Janet Woodcock said in a press release. "Vaccines have proven to be the best and highly effective defense against COVID-19."

A healthcare professional is administering a vaccine.

Image source: Getty Images.

Woodcock said booster shots will offer better protection against the most serious potential effects of the disease, including hospitalization and death. Health officials also said that expanding the eligibility criteria to all U.S. adults would help reduce confusion about who could get one. The FDA had previously authorized booster shots for people 65 years of age and older, younger individuals who were at high risk of severe COVID-19, and adults with "frequent institutional or occupational exposure" to the novel coronavirus.

Now what 

Shortly before the market close, an advisory committee for the Centers for Disease Control and Prevention (CDC) voted in favor of booster shots. CDC Director Rochelle Walensky is now expected to sign off on the additional vaccine doses in short order. 

That would pave the way for Moderna to begin supplying doses to tens of millions of Americans who received their primary series of its COVID-19 vaccine earlier this year.

"This emergency use authorization comes at a critical time as we enter the winter months and face increasing COVID-19 case counts and hospitalizations across the country," Moderna CEO Stéphane Bancel said.