WASHINGTON • American adults who haven’t yet gotten vaccinated against COVID-19 might soon get another choice, as advisers to the Food and Drug Administration on Tuesday backed a more traditional type of shot.

Next, the FDA must decide whether to authorize the protein vaccine made by latecomer Novavax as the nation’s fourth coronavirus shot for adults. It’s made with more conventional technology than today’s dominant Pfizer and Moderna shots and the lesser-used Johnson & Johnson option.

Novavax shots are available in Australia, Canada, parts of Europe and multiple other countries, either for initial vaccinations or as mix-and-match boosters. But U.S. clearance is a key hurdle for the Maryland-based company. FDA’s vaccine chief Dr. Peter Marks said another choice in the U.S. may entice at least some vaccine holdouts — whatever their reason — to consider rolling up their sleeves.

“We do have a problem with vaccine uptake that is very serious in the United States,” Marks said. “Anything we can do to get people more comfortable to accept these potentially life-saving products is something that we feel we are compelled to do.”

A final FDA decision isn’t expected immediately, as the agency finishes combing through the data. Nor is it clear how widely a Novavax vaccine would be used, at least right away. Only about 27 million U.S. adults remain unvaccinated, according to the Centers for Disease Control and Prevention. Eventually, Novavax hopes also to become a choice for the millions more who haven’t yet had a booster dose of today’s vaccines, regardless of which shot people got originally.

The FDA advisory panel voted that the benefits of two primary Novavax doses outweigh its risks — but they had a lot of questions about the shots’ role at this point in the pandemic. “This vaccine does indeed fill some unmet needs,” such as an option for people with allergies to competing shots, said Dr. Michael Nelson of the University of Virginia.