The U.S. Food and Drug Administration (FDA) granted full approval to Moderna's (MRNA  ) COVID-19 vaccine on Monday for individuals 18 years of age and older, making it the second COVID vaccine to receive full regulatory approval in the United States.

The full approve of Moderna's m-RNA vaccine, marketed as Spikevax, came about five month after the company had finalized its applications for regulatory approval. The FDA's latest approval follows rival Pfizer (PFE  ) and partner BioNTech's (BNTX  ) COVID m-RNA vaccine approval in August for use in people aged 16 years or older.

"This is a momentous milestone in Moderna's history as it is our first product to achieve licensure in the U.S.," said CEO Stephane Bancel in a press statement. "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. The totality of real-world data and the full [approval] for Spikevax in the United States reaffirms the importance of vaccination against this virus."

The vaccine has previously been in use for more than a year in the U.S. under a FDA emergency use authorization (EUA), which it received in December 2020. Over 204 million doses of Moderna's vaccine have been administered in the U.S., according to data compiled by the U.S. Centers for Disease Control and Prevention (CDC), with nearly 75 million people have been fully vaccinated with it. Moreover, over 39 million booster shots of the vaccine have been administered, according to CDC data.

"While hundred of millions of doses of Moderna COVID-19 vaccine have been administered to individuals under emergency use authorization, we understand that for some individuals, FDA approval of this vaccine may instill additional confidence in making the decision to get vaccination," Dr. Janet Woodcock, acting FDA commissioner, said in a press statement on Monday.

Moderna's vaccine still remains available under EUA as a third primary series dose for individuals 18 years of age or older who have weakened immune systems, and as a single booster dose for adults at least five months after completing a primary two-dose series. Some immunocompromised individuals are also eligible for a fourth dose under an EUA.