WASHINGTON — The US Food and Drug Administration (FDA) announced Monday that it has granted full approval to Moderna’s Covid-19 “Spikevax” vaccine, which had previously received an emergency use authorization in the United States.

“The public can be assured that Spikevax meets the FDA’s high standards for safety, effectiveness and manufacturing quality required of any vaccine approved for use in the United States,” acting FDA commissioner Janet Woodcock said in a statement.

“The FDA’s approval of Spikevax is a significant step in the fight against the Covid-19 pandemic, marking the second vaccine approved to prevent Covid-19,” Woodcock said.

The full approval of the Moderna vaccine is for individuals aged 18 or older.

A Pfizer vaccine for individuals aged 16 or older received full FDA approval at the end of August.

Woodcock said she hoped FDA approval of the Moderna vaccine “may instill additional confidence in making the decision to get vaccinated.”

Moderna CEO Stephane Bancel called the FDA move a “momentous milestone” for the company.

“Our Covid-19 vaccine has been administered to hundreds of millions of people around the world, protecting people from Covid-19 infection, hospitalization and death,” Bancel said in a statement.

The Moderna vaccine received an emergency use authorization in December 2020.

The full approval from the FDA concerns the first two doses of the Moderna vaccine. A booster dose remains under an emergency use authorization.

The FDA said clinical trials to determine the effectiveness of Spikevax included 14,287 vaccine recipients and 14,164 placebo recipients.

The most common side effects by clinical trial participants were pain at the injection site, fatigue, headaches, muscle or joint pain, chills, nausea or vomiting and swollen lymph nodes, the FDA said.

It said there was an increased risk in men aged 18 to 24 of myocarditis — inflammation of the heart muscle — and pericarditis — inflammation of tissue surrounding the heart — following vaccination with the second dose.

But, the FDA said, it has determined that the “benefits of the vaccine outweigh the risk of myocarditis and pericarditis in individuals 18 years of age and older.”