The vaccinations will be offered to critical personnel in all three branches of government deemed essential, and could start as soon as Monday. The shots will be staggered over the following 10 days to ensure staff don’t experience possible side effects all at the same time.

Trump said in a tweet on Sunday, following reports about the plan, that he had directed that top government officials would be vaccinated “somewhat later.” He said he personally is not “scheduled” to be vaccinated.

The measure also comes as health officials seek to build public confidence in the treatment. Offering the vaccine to top government members was recommended by public health officials and career national security staff, according to the people.

National Security Council spokesman John Ullyot confirmed the plan in a statement late Sunday.

“The American people should have confidence that they are receiving the same safe and effective vaccine as senior officials of the United States government on the advice of public health professionals and national security leadership,” Ullyot said.

President-elect Joe Biden will follow the guidance of Anthony Fauci, the U.S. government’s top infectious disease expert, about when to take a coronavirus vaccine and will have it administered in public, a transition official said.

In general, the first people in the U.S. to get the Pfizer Inc./BioNTech SE vaccine approved on Friday will be health-care workers and vulnerable residents of care homes. Various other groups, from airline workers to teachers to meatpackers, are keen for early access too.

U.S. health officials on Sunday warned that skepticism about the vaccines among many Americans may be a barrier to the nation achieving “herd immunity” against the coronavirus.

“The way we get through this is to achieve herd immunity,” U.S. Food and Drug Administration chief Stephen Hahn said on ABC. “And that means we need to vaccinate a significant number of people in this country, including those who are hesitant.”