The U.S. Food and Drug Administration (FDA) issued an emergency use authorization on Wednesday for the Novavax COVID-19 vaccine in individuals aged 18 and older, making it the fourth vaccine available in the United States, but one which uses technology different from previous approvals.

In a statement, the FDA said the vaccine, whose known and potential benefits outweigh risks in adults, may be effective in preventing COVID-19 and will be available as a two-dose primary series for adults, three weeks apart.

The Advisory Committee on Immunization Practices at the U.S. Centers for Disease Control and Prevention (CDC) is scheduled to meet on July 19 to weigh in on the vaccine, and the CDC director will ultimately decide on whether to sign off on its recommendation before nationwide administration is approved.

Earlier this week, the U.S. government said it had secured 3.2 million Novavax vaccine doses, which it plans to release once the company finishes quality testing in the next few weeks.

More than two-thirds of the U.S. population has been fully vaccinated with shots from Moderna, Pfizer-BioNTech or Johnson & Johnson.

U.S. health officials hope that people who have opted not to take Pfizer and Moderna's vaccine, which are based on the groundbreaking messenger RNA (mRNA) technology, will instead opt for Novavax's protein-based shot.

The vaccine, already approved in Europe, is based on a technology that has been used for decades to combat diseases including hepatitis B and influenza.

"Today's authorization offers adults in the United States who have not yet received a COVID-19 vaccine another option that meets the FDA's rigorous standards," FDA Commissioner Robert Califf said in a statement.

In Europe, however, demand for the shot has not been significantly high, with about 242,000 doses of the vaccine administered since its launch in December, prompting Novavax to increase its focus on lower-income countries.

The company's initial application for U.S. authorization of the shot was delayed by almost a year on development and production problems, making it a late entrant in the country's market for COVID-19 vaccines.

Novavax has projected between $4 billion and $5 billion in sales this year. Analysts expect sales at the lower end of that range, according to Refinitiv.

(With input from agencies)