The White House has repeatedly refused to say who else has tested positive, even as the virus continues to spread. The latest White House cluster, coming just a month after Trump’s own diagnosis and hospitalisation, includes a top Trump campaign official as well as a handful of undisclosed White House staff, officials said.

US election 2020: Joe Biden works on coronavirus plan as Donald Trump golfs

The White House has been increasingly secretive about outbreaks. Many White House and campaign officials, as well as those who attended the election watch party, were kept in the dark about the diagnoses, unaware until they were disclosed by the press.

That the virus would continue to spread in the White House – even though senior staff and those who come into close contact with the president and vice-president were frequently tested – has come as no surprise to public health officials who have balked at the White House’s lax approach.

“The administration was cavalier about the risks of the virus for themselves and for the country. And that’s one reason why we have so many cases,” said Dr Joshua Sharfstein, a public health professor at Johns Hopkins University’s school of public health.

01:00

Trump claims he has won the 2020 presidential election, with millions of votes still to count

Trump claims he has won the 2020 presidential election, with millions of votes still to count

Even Senate Majority Leader Mitch McConnell has said he has been avoiding the White House since August “because my impression was their approach to how to handle this was different from mine and what I insisted that we do in the Senate, which is to wear a mask and practice social distancing”.

Meadows in particular has long tried to play down the severity of the virus. He rarely wore a mask in public, except during the period immediately following Trump’s infection. At one point, he refused to speak to reporters on Capitol Hill after they requested he wear a mask.

Worldwide coronavirus cases surge past 50 million after 30-day spike

He was again without one during Tuesday evening’s East Room event, where more than 100 of Trump’s most loyal supporters gathered to watch the election results come in and see him deliver what they had hoped would be a victory speech.

It was a festive atmosphere, with half-empty glasses of wine and other beverages strewn across cocktail tables in front of news cameras. Meadows, who spent time with Trump’s family beforehand, was seen working the room, including giving several fist-bumps to those in attendance, before Trump took the stage early Wednesday morning.

While everyone who attended the East Room event had been tested in advance for the virus, there was no social distancing and minimal mask-wearing.

Earlier that day, Meadows had also accompanied the president to his campaign’s headquarters in Virginia, where Trump received rousing cheers from several dozen staff and volunteers. Meadows did not wear a mask, nor did other White House staffers. Campaign aides largely did.

If Meadows tested positive Wednesday – as Bloomberg News reported – he would likely have been infectious during both events, said Saskia Popescu, an epidemiologist who teaches at George Mason University.

AstraZeneca CEO says coronavirus vaccine could be ready in December

Meadows had also travelled with Trump in the run-up to election day, attending dozens of rallies where he was frequently seen interacting with supporters without masks.

Trump’s refusal to abide by his own government’s public health guidelines throughout the campaign was a major source of frustration for local governments as he scheduled rally after rally in defiance of local caps on crowd sizes, even in pandemic hot zones.

While Trump had hoped his efforts to play down the virus in a bid to revive a limping economy would help him with voters, many Republicans now believe that Trump might have won re-election had he handled things differently.

The White House did not respond to specific questions about the current outbreak, but said that contact tracing had been conducted by the White House Medical Unit, consistent with Centres for Disease Control and Prevention guidelines.

“Appropriate notifications and recommendations have been made,” the White House said.

The CDC defines “close contact” as spending at least 15 minutes within about 2 metres (6 feet) of an infected person beginning two days before they test positive or exhibit symptoms.

But Popescu called the party, in particular, “a ripe environment for transmission to occur,” and said anyone in attendance should have been informed and asked to take precautions.

“While they might not meet CDC guidelines for exposure, I think when we’re looking at an indoor event with a lot of people for a prolonged period who are unmasked, out of an abundance of caution, everyone should be notified and encouraged to stay home,” she said.

“Now is not the time to be cavalier about the risks,” Sharfstein said.

Ohio pastor Darrell Scott, a close ally of the president who attended the party, said he was unaware any White House officials beyond Meadows had tested positive until informed by a reporter and had not been contacted by any tracer.

While Scott, like many in Trump’s orbit, continued to insist fraud was to blame for the president’s loss – despite no credible evidence supporting those claims – he also blamed Trump for several “unforced errors” during the campaign, including the way he talked about the virus.

“I can’t be upset if we shoot ourselves in the foot,” he said.

The latest outbreak came less than two weeks after several aides to Vice-President Mike Pence, including his chief of staff, tested positive for the virus. And it came a month after Trump, first lady Melania Trump and at least two dozen others tested positive after Trump held large gatherings of people not wearing face masks, including the ceremony announcing the nomination of Judge Amy Coney Barrett to the Supreme Court.