(CNN) Then-President Donald Trump tested positive for Covid-19 three days ahead of his first 2020 presidential debate with Joe Biden -- though he also had a negative result in that same timeframe, according to excerpts from a forthcoming book from the former Republican president's chief of staff reported by The Guardian.
The previously unknown positive test is disclosed in Trump's former chief of staff Mark Meadows' memoir "The Chief's Chief," a copy of which was obtained by The Guardian ahead of the book's publication next week.
Trump said in a statement Wednesday, "the story of me having COVID prior to, or during, the first debate is Fake News. In fact, a test revealed that I did not have COVID prior to the debate."
CNN has reached out to Meadows and then-White House physician Dr. Sean Conley for comment.
Trump received the positive test on September 26, 2020, according to Meadows, The Guardian reported. That day Trump hosted a ceremony in the White House Rose Garden for Supreme Court nominee Amy Coney Barrett, which was later deemed a super spreader event, by medical experts. At least 12 people who attended the event tested positive.
Trump, who Meadows said looked "a little tired," was en route to a rally in Middletown, Pennsylvania, that night when Meadows received a call from Conley informing him that Trump tested positive for Covid-19, according to the excerpt. Meadows wrote that Conley told him, "Stop the president from leaving. He just tested positive for Covid."
Meadows claims in his book that the positive test was done with an old model kit, The Guardian reported.
Trump was subsequently tested with "the Binax system" an antigen test for Covid-19, and returned a negative result, Meadows wrote. It is unclear if the first test which returned the positive result was an antigen test or PCR test.
According to the FDA's guidelines, when using the Binax test, "Negative results do not rule out SARS-Covid-2 infection and should not be used as the sole basis for treatment or patient management decisions, including infection control decision."
Meadows wrote that Trump took the negative test as "full permission to press on as if nothing had happened," but Meadows instructed those in Trump's "immediate circle to treat him as if he was positive," The Guardian reports.
"I didn't want to take any unnecessary risks," Meadows wrote, according to The Guardian, "but I also didn't want to alarm the public if there was nothing to worry about."
A former senior White House official told CNN that word had circulated inside the West Wing before the first presidential debate that Trump had tested positive for Covid.
In between those dates, Trump appeared at a White House reception for Gold Star families and held a press briefing indoors on September 27, 2020. He also visited his golf club in Sterling, Virginia, earlier that day, according to pool reports.
The following day, Trump held an event on the South Lawn of the White House, where he met with workers from Lordstown Motors, and later appeared in the White House Rose Garden to hail a new testing strategy for coronavirus.
On September 29, 2020, Trump traveled to Cleveland for his first presidential debate against his Democratic challenger Joe Biden. Trump arrived too late to be tested ahead of the debate, according to Fox News' anchor Chris Wallace, who moderated the debate.
During the debate, Trump and Biden adhered to social distance protocols, but the two candidates -- both in their 70s -- were indoors in a room with dozens of people in the audience, some of whom were not masked.
Trump on September 30 traveled to Minnesota for an outdoor rally in Duluth and a private fundraiser in Minneapolis.
Trump announced early Friday, October 2, 2020 that he and first lady Melania Trump tested positive for Covid-19. He was hospitalized later that night.
According to the White House, Trump tested positive for the coronavirus on October 1, just two days after the debate.
In a later interview with NBC News, Trump would not definitively say whether he was tested for Covid-19 on the day of his first debate against Biden and said he could not recall the last time he tested negative for coronavirus before testing positive on October 1.
During a news conference on October 3, 2020, as Trump was receiving treatment at Walter Reed National Military Medical Center for Covid, Conley would not disclose Trump's last negative test for the virus, saying, "I'm not going to get into all the testing going back, but he and all his staff routinely are tested."
In his book, Meadows wrote that although he knew each candidate was required to test negative within 72 hours of the debate's start time "...Nothing was going to stop [Trump] from going out there," The Guardian reported.
After the then-president announced he had Covid, Meadows was refusing to tell his own staffers the precise timeline of when Trump had tested positive at the time, the former senior White House official added.
The official went on to say the virus simply was not taken seriously by some senior aides.
Staffers were sometimes in meetings and around other aides before going home sick with Covid.
"There was a bizarre indifference about getting others sick among some people in the west wing," the official said.
A separate aide also said Meadows was keeping staffers in the dark about exact details of Trump's illness.
Asked Wednesday about The Guardian report and whether he thought Trump put him at risk at the time, Biden told White House reporters, "I don't think about the former President."
This story has been updated with additional information.