US President Donald Trump has reversed a plan for White House officials to receive the coronavirus vaccine in the coming days.
Officials had said senior members of the Trump administration would be among the first people to be given the Pfizer/BioNTech jab.
But Mr Trump said he had asked for an “adjustment” to be made to the plans.
The US has approved the vaccine for emergency use and will begin to roll it out on Monday.
The vaccine offers up to 95% protection against Covid-19.
The first three million doses of the vaccine are currently being distributed to dozens of locations in all 50 states across the US.
The first shipment of those doses left a facility in Michigan on Sunday, with health workers and the elderly in line to receive the first shots.
Coronavirus deaths have been rising sharply since November in the US, with a world-record daily increase of 3,309 reported on Saturday.
The vaccine’s rollout has been framed as a turning point in the coronavirus pandemic, which has taken the lives of almost 300,000 people in the US.
The Pfizer vaccine has received regulatory approval in Canada, Bahrain and Saudi Arabia as well.
The beginning of the vaccination drive in the US comes as the Electoral College – the system which elects US presidents – is set to endorse Joe Biden’s victory on Monday.
When will Trump receive the vaccine?
Officials told several media outlets on Sunday that some of the first vaccines would be reserved for those who work in close proximity to Mr Trump.
The vaccination plan, first reported by the New York Times, was confirmed by National Security Council (NSC) spokesman John Ullyot.
One aim of the programme was to build public confidence in the vaccine, he said.
“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,” Mr Ullyot said.
But Mr Trump on Sunday suggested that top officials would now have to wait longer.
“People working in the White House should receive the vaccine somewhat later in the program, unless specifically necessary,” he said in a tweet. “I have asked that this adjustment be made.”
It was not immediately clear what effect Mr Trump’s tweet would have on the government’s efforts to protect top officials, AP news agency reports.
The US president, who contracted coronavirus in October and recovered after treatment in hospital, said he was not yet scheduled to take the vaccine but looked forward to doing so “at the appropriate time”.
He has previously claimed to be “immune”, even though medical experts say it is unclear whether people who have recovered from Covid-19 are protected from a second infection, and if so, how long this protection might last.
There have been a number of coronavirus outbreaks in the White House, with several senior staffers and officials testing positive for the disease.
The latest is Mr Trump’s personal lawyer, Rudy Giuliani, who revealed last week that he was being treated with the same drug cocktail as the president.