The Centers for Disease Control and Prevention on Tuesday recommended Novavax’s two-dose Covid vaccine, paving the way for 3.2 million doses to get shipped to states. The Food and Drug Administration authorized the Novavax vaccine for emergency use last week, but the CDC had to sign off before doses could be distributed to the public. An independent advisory panel to the CDC voted unanimously to recommend the vaccine on Tuesday, then CDC Director Dr. Rochelle Walensky endorsed the panel’s recommendation shortly after.Some public health officials hope shot will fill a gap in the U.S. vaccination push, since it does not use mRNA technology. Around 22% of people in the U.S. still have not received a single Covid vaccine, according to the CDC. "If you have been waiting for a Covid-19 vaccine built on a different technology than those previously available, now is the time to join the millions of Americans who have been vaccinated,"  Walensky said in a statement on Tuesday. "With Covid-19 cases on the rise again across parts of the country, vaccination is critical to help protect against the complications of severe Covid-19 disease." In a presentation to the advisory panel Tuesday, CDC officials said that people ages 18 and older who are not immunocompromised should get the two doses of Novavax's vaccine three to eight weeks apart. Those who are immunocompromised should receive two doses three weeks apart.The vaccine has already been authorized in more than 40 countries and the European Union. More than 1 million doses had been administered worldwide as of June 30, Novavax said Tuesday. Novavax’s vaccine stimulates the production of antibodies by introducing the body to a purified spike protein from the coronavirus, along with an immune-boosting ingredient called an adjuvant. The FDA has approved several protein-based vaccines in the past, including one for hepatitis B and another for shingles. Pfizer-BioNTech's and Moderna's vaccines, by contrast, were the first mRNA vaccines authorized. They use a snippet of the coronavirus’s genome to instruct the body to produce the spike protein internally, which triggers the development of antibodies. However, the availability of Novavax shots may not significantly alter U.S. vaccination rates at this point. In a small CDC survey conducted early this year, just 16% of unvaccinated respondents said they would probably or definitely get a protein-based Covid vaccine. And a June survey from Morning Consult found that 77% of unvaccinated adults said they would not get a protein-based Covid shot if one were authorized in the U.S.

Novavax’s vaccine comes with another advantage, though: It can be stored in a regular refrigerator for up to six months, so it's easier to transport than mRNA vaccines, which must be kept at subzero temperatures.