The three COVID-19 vaccines available in the U.S. were granted Emergency Use Authorization by the Food and Drug Administration, which means that when the emergency ends, Pfizer, Moderna, and Johnson & Johnson will have to file a separate application to the FDA to be fully licensed.

Right now, the Centers for Disease Control and Prevention says that as many as one-third of Americans in some areas of the country are hesitant about getting the COVID-19 vaccine.

Dr. Anthony Fauci said that the emergency authorization may be fueling vaccine hesitance. When people hear “it’s still emergency use, they still have a little concern about how far you can go with it,” he told CNN. Legally, organizations and companies may not be able to mandate vaccinations, according to CNBC, unless they are fully licensed by the FDA.

But since all phases of clinical trials have already been done for the COVID-19 vaccines  on the market, and the FDA has reviewed the safety and manufacturing data provided by the pharmaceutical companies, the formal approval process could happen “very soon,” Fauci, director of the National Institute of Allergy and Infectious Diseases, said.

Once the drugs pass the evaluation, experts believe skeptics may change their minds.

Dr. Jerome Adams, the U.S. surgeon general during the Trump administration, said that “we can’t reach the COVID-19 finish line with only half the herd.”

In an opinion piece he wrote for The Washington Post, Adams said that “many people who are lower risk understandably ask if the benefits justify taking a medication that has not received the full and traditional FDA stamp of approval.” He said that as the manufacturers complete further studies, “it will help show skeptics that the authorized COVID-19 vaccines are safe.”

Fauci said the FDA will work “as expeditiously as possible” on approval applications when they come in. Moving from EUA to full approval means that the drug companies will have the power to market and distribute their products themselves. Full FDA approval also may convince those who are still reluctant to get the vaccine that the drugs are safe and effective.

“When you are getting a formal approval, you have to have a certain amount of time just observing predominantly the safety — and obviously the safety looks really, really good in well over 140 million people having been vaccinated with at least a single dose,” said Fauci.

The three pharmaceutical companies will need to submit a Biological License Application or BLA to the FDA to secure licensing.

“FDA’s Center for Biologics Evaluation and Research (CBER) ensures that FDA’s rigorous scientific and regulatory processes are followed by those who pursue the development of vaccines,” says the FDA website, adding that their evaluation of the safety and effectiveness of vaccines is “among the most robust in the world.”

The University of California and California State University Systems announced they intend to require staff and students get COVID-19 vaccines but only “upon full FDA approval,” says CNN.