[July 20 editor's note: The U.S. Centers for Disease Control and Prevention now recommends the Novavax COVID-19 vaccine for adults.]

A protein-based COVID-19 vaccine could soon be available for the first time in the United States. On July 13 the U.S. Food and Drug Administration authorized Novavax's vaccine for emergency use in adults age 18 and older. An authorization from the Centers for Disease Control and Prevention is still needed before Americans could begin to receive the two-dose series.

“It's a vaccine that is more like traditional vaccines for hepatitis B or human papillomavirus,” said Dr. Scott McClelland, professor of medicine at the University of Washington School of Medicine. “There are over 40 countries that have already approved use of the Novavax vaccine, so it’s in use in a lot of places.”

The UW Medicine Virology Research Clinic was one of several sites throughout the United States and Mexico to measure the safety and effectiveness of the Novavax vaccine during a Phase III clinical trial, which enrolled nearly 500 participants.

“The primary results [of the trial] showed overall 90% efficacy at preventing any symptomatic infection,” said McClelland. “But like the other vaccines, we expect some decrease in the effectiveness as the variants get further and further from the original protein that the vaccine was developed for.”

McClelland says the vast majority of side effects reported during the trial were mild.

“Most commonly, things like a sore arm or a headache,” said McClelland. “The rate of myocarditis was similar in the placebo recipients and in the vaccine recipients, and was down into the .005-to-.007 percent range. But it's something that certainly the FDA will be continuing to watch for as the vaccine goes to more people.”

Download broadcast-ready soundbites on the Novavax COVID-19 vaccine.