A team from San Mateo County Health's Street & Field Medicine vaccinates individuals experiencing homelessness at a clinic at a church in San Bruno, Calif. on March 25, 2021. (Photo courtesy the County of San Mateo Joint Information Center)

The U.S. Food and Drug Administration issued an Emergency Use Authorization Wednesday for the COVID-19 vaccine developed by the Maryland-based biotechnology company Novavax, the fourth COVID vaccine available in the U.S.

The two-dose vaccine, administered three weeks apart, will be available to adults and is the first available in the U.S. with a traditional vaccine composition using non-infectious pieces of coronavirus particles.

Trials with some 30,000 adults in the U.S. and Mexico found the vaccine to be 90.4 percent effective at preventing mild, moderate and severe cases of the virus.

However, those trials were conducted prior to the emergence of the delta and omicron variants, according to the FDA.

“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 for safety, effectiveness and manufacturing quality needed to support emergency use authorization,” FDA Commissioner Dr. Robert Califf said.

An FDA advisory panel voted 21-0, with one abstention, last month to recommend an emergency use approval for the vaccine.

Commonly reported side effects of the vaccine were similar to the other three available in the U.S., including fatigue, muscle and joint pain, headaches, fever and pain, tenderness, redness and swelling at the injection site.

As of Wednesday, 67 percent of all U.S. residents have completed their initial vaccination series. Of those, nearly 48 percent have also received at least one booster dose to bolster their immune protection.