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President Donald Trump has tested negative for the coronavirus and is “not infectious to others,” his doctor announced Monday, but other physicians are questioning those findings, noting the test does not appear to have been used for its intended purpose.
The memo from Trump’s doctor, Sean Conley, came shortly before the president went to Florida for a rally. This was some 10 days after Trump announced that he had tested positive for COVID-19. The CDC recommends that patients isolate for at least 10 days after symptoms first appear, and possibly up to 20 days in severe cases.
Trump “has tested NEGATIVE, on consecutive days, using the Abbott BinaxNOW antigen card,” Conley wrote, referring to an antigen test made by the company Abbott Laboratories that can detect a SARS-CoV-2 infection in under 15 minutes.
Antigen tests, which look for proteins on the virus’s surface, are much faster and cheaper than the gold-standard polymerase chain reaction (PCR) tests, which look for the genetic material of the virus.
Based on those test results and other information, Conley wrote, the medical team determined that “in concert with the CDC’s guidelines for removal of transmission-based precautions … the President is not infectious to others.” In a previous memo over the weekend, Conley had cleared Trump to return to an active schedule because he was “no longer considered a transmission risk to others.”
But other doctors noted that the CDC does not recommend using antigen tests to clear sick patients from isolating.
“That’s not the purpose of the test,” Megan Ranney, an emergency physician and researcher at Brown University, told BuzzFeed News. “They’re selectively reporting testing to somehow make the case he’s not infectious.”
The CDC’s website states that it “does not recommend using antigen tests to make decisions about discontinuing isolation.” For patients who have COVID-19 symptoms or had a known exposure to someone infected, it recommends confirming negative antigen tests with a PCR test.
“We want to know his PCR test information. That’s the information we’re curious about,” said Krutika Kuppalli, an assistant professor of medicine at the Medical University of South Carolina.
Antigen tests are most likely to capture an infection at its peak. Due to their relative ease and affordability, they are considered useful for screening people who are asymptomatic. They also indicate whether the virus is present, whereas PCR tests can evaluate the levels of the virus. Overall, antigen tests are not as good as PCR tests in terms of picking up small traces of the virus.
Abbott’s BinaxNow test has a sensitivity rate of 97.1%, according to the company, meaning it will return false-negative results for about 3% of people who are infected and should have tested positive. The company also recommends that in patients who are beyond a week from when their symptoms started, negative results “should be treated as presumptive” and confirmed with a PCR test. “Negative results do not rule out SARS-CoV-2 infection and should not be used as the sole basis for treatment or patient management decisions, including infection control decisions,” company documents state.
The Trump administration has championed this particular test as a tool to help expand the nation’s testing capacity. In August, the day after the FDA granted the tests an emergency use authorization, the Department of Health and Human Services announced that it planned to distribute 150 million of the tests nationwide.
Conley’s memo stated that the Abbott antigen test “was not used in isolation for the determination of the President’s current negative status,” and that Trump had taken a PCR test. But it gave no information about the results of that test, nor did it go into detail about the other factors that helped inform the diagnosis.
In the memo, Conley stated that “additional clinical and laboratory data, including viral load, subgenomic RNA, and PCR cycle threshold measurements, as well as ongoing assessment of viral culture data, all indicate a lack of viral replication.”
“PCR cycle threshold measurements” refers to the number of cycles of polymerase chain reactions that need to be run in order to detect the virus. When a sample has a very high viral load, fewer cycles are needed in order to amplify the virus enough to detect it. Conversely, the lower the viral load is in the sample, the more cycles that are needed to pick up on it.
Conley’s memo did not specify what Trump’s “cycle threshold measurements” were. Even if the number were low, “a smaller amount of virus does not mean no virus,” said Ranney, the Brown University researcher. It also doesn’t necessarily mean that someone is or isn’t infectious to others.
Angie Rasmussen, a virologist at Columbia University, noted that the antigen test is “less sensitive than ALL those other tests” mentioned by Conley. “So I am wondering why the negative result is being reported only from that,” she told BuzzFeed News. “Why not share the data?”
Doctors told BuzzFeed News they did not have enough information to know whether the president was or was not infectious as of Monday night, when he traveled on Air Force One and spoke to supporters at his rally — but they said that he should take precautions either way.
“Regardless of the team’s assessment of whether he’s infectious to others or not, he needs to follow his own CDC’s guidelines about the lengths of times for isolation,” Ranney said. “He also needs to follow his own CDC’s guidelines around masking and physical distancing regardless of whether he’s infectious or not.”
To be on the safe side, that would mean isolating for 20 days, said Carlos del Rio, a professor of medicine at Emory University School of Medicine.
Signs indicate that Trump’s case was not mild: He took a steroid recommended by the World Health Organization and the National Institutes of Health only for severe to critical cases, and he needed supplemental oxygen at least twice when his oxygen levels dropped.
“Either he had severe disease, and that’s why he took the meds he took — or he didn’t have severe disease and didn’t need the meds they gave him,” del Rio said. “You can’t have it both ways.”
In what is now a common pattern, Monday’s memo raised more questions than it answered, doctors said. Conley did not specify which “consecutive days” the president tested negative, nor did he give any information about his symptoms.
In Saturday’s update, Conley said Trump had been fever-free for “well over 24 hours” but didn’t say if he was on any fever-reducing treatments.
“Without knowing what symptoms the president had, it’s difficult to make any accurate conclusions,” Kuppalli said. “We always have to read between the lines in these press statements.”
In both the memos from Saturday and Monday, Conley referenced “subgenomic mRNA” and “subgenomic RNA” as signs that the virus was below detectable levels — a disclosure that confused at least a few medical experts. “I don’t know what the hell that means,” del Rio said. “That’s mumbo jumbo.”
On Sunday morning, Trump tweeted that he’d gotten “a total and complete sign off from White House Doctors yesterday. That means I can’t get it (immune), and can’t give it. Very nice to know!!!” he wrote. Twitter flagged the claim as “misleading” and “potentially harmful.”
A White House spokesperson did not immediately return a request for comment.