LOS ANGELES - The US Food and Drug Administration (FDA) on Wednesday issued an emergency use authorization (EUA) for the Novavax COVID-19 vaccine in individuals 18 years of age and older.

The Novavax vaccine will be available as two-dose primary series for adults, three weeks apart.

The known and potential benefits of the vaccine outweigh its known and potential risks in people 18 years of age and older, and the vaccine may be effective in preventing COVID-19, said the FDA in a statement.

It is the fourth COVID-19 vaccine available in the United States, and it uses a different type of vaccine technology from the other three approved vaccines.

The Novavax vaccine contains the SARS-CoV-2 spike protein and Matrix-M adjuvant. Adjuvants are incorporated into some vaccines to enhance the immune response of the vaccinated individual, according to the FDA.

The vaccine was assessed in an ongoing randomized, blinded, placebo-controlled study conducted in the United States and Mexico. Overall, the vaccine was 90.4 percent effective in preventing mild, moderate or severe COVID-19, according to the FDA.

The most commonly reported side effects of the vaccine include pain, redness and swelling at the injection site, fatigue, muscle pain, headache, joint pain, nausea and fever, said the FDA.

"Authorizing an additional COVID-19 vaccine expands the available vaccine options for the prevention of COVID-19, including the most severe outcomes that can occur such as hospitalization and death," said FDA Commissioner Robert M. Califf.

"After a comprehensive analysis and evaluation of the data, and assessment of the manufacturing processes and information, as well as input from the FDA's committee of external independent advisors, the FDA's medical and scientific experts have determined that the vaccine meets the FDA's high standards for safety and effectiveness for emergency use authorization," said Peter Marks, director of the FDA's Center for Biologics Evaluation and Research.

The independent vaccine advisers of the US Centers for Disease Control and Prevention (CDC) will weigh in on whether to recommend the vaccine, and the CDC director will decide on signing off on the recommendation before the vaccine is ready to be administered in the country.

The CDC's Advisory Committee on Immunization Practices is scheduled to meet on July 19.

On Monday, the US administration announced that it had secured 3.2 million doses of the Novavax vaccine.