The Food and Drug Administration (FDA) signed off Wednesday on an emergency use authorization for the Novavax COVID-19 vaccine for individuals 18 years of age and older.

The Novavax vaccine is protein-based. It's made with a more conventional technology than the Pfizer and Moderna shots, which used mRNA technology.

“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 Dr. Robert M. Califf.

The Novavax vaccine is authorized for a two-dose primary series, which should be given three weeks apart. In clinical trials, Novavax said the most common side effects were headache, nausea, injection site tenderness and fatigue.

The Centers for Disease Control still needs to sign off on the vaccine.

In anticipation of getting the green light from health officials, the Biden administration announced Monday that it would purchase 3.2 million doses of the vaccine.

It will be offered at no cost to states and federal partners.