The Centers for Disease Control and Prevention (CDC) has officially endorsed Novavax – a more traditional kind of vaccine – for U.S. adults who remain unvaccinated against COVID-19.

Just last week, the U.S Food and Drug Administration cleared the so-called protein vaccine for COVID-19. But the final hurdle was securing a recommendation from the CDC.

In a recent press release, however, CDC director Dr. Rochelle Walensky stated that their committee of independent advisors voted unanimously to recommend the vaccine for people 18 years old and above.

“Today, we have expanded the options available to adults in the U.S. by recommending another safe and effective COVID-19 vaccine. 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.

For the past two years, most Americans have already gotten at least their primary vaccination against COVID-19. However, CDC officials said that there are still 26-37 million adults who haven’t had a single dose yet – and this population is the one that Novavax will be targeting for now.

“We really need to focus on that population,” added CDC adviser Dr. Oliver Brooks, the past president of the National Medical Association, saying that he hopes the vaccine will finally convince the unvaccinated.

The approval and endorsement from the CDC complete the two-year journey for Novavax, one of the early participants in the U.S. to produce a COVID-19 vaccine. Now, Novavax’s vaccine will enter the country at a time when around 77% are fully vaccinated with Pfizer, Moderna, and Johnson & Johnson shots.

Based on clinical trial data, the vaccine is 90% effective at preventing overall illness and 100% effective at stopping severe disease when the alpha COVID variant was still dominant. The company has not yet published data regarding the vaccine’s real-world effectiveness against omicron and its subvariants.

Unlike Pfizer and Moderna’s shots, the Novavax vaccine is based on protein subunit technology, the same technology used in flu, whooping cough, and hepatitis B vaccines.

The vaccines are stored at refrigerator temperatures, compared to Pfizer and Moderna’s shots that require a subzero environment.