The onset date of Mr. Trump’s symptoms has also remained unclear. According to Dr. Conley’s assessment, Mr. Trump should have shown signs of his illness on Wednesday, September 30 for Saturday to qualify as 10 days after the onset of symptoms. Most people stop being contagious on day 10 after they start feeling sick, CDC says
“Tonight, I am pleased to report that in addition to the president meeting CDC criteria for safe termination of isolation, this morning’s Covid PCR sample demonstrates, by currently recognized standards, that it is no longer considered a risk of transmission to others, ”Dr. Conley wrote. “Now on day 10 after symptom onset, fever free for more than 24 hours and all symptoms have improved, the resulting assortment of advanced diagnostic tests reveals there is no longer any evidence of active replication virus. In addition, sequential testing throughout his illness demonstrated a decrease in viral load that correlates with increased cycle threshold times, as well as a decrease in now undetectable subgenomic mRNA.
Several experts expressed skepticism about the wording describing Mr. Trump’s diagnostic tests, which did not explicitly categorize the president as “negative” for the coronavirus. PCR, a lab technique that detects the genetic material of the virus, can give researchers a rough idea of how much virus is left in a person’s body or the viral load. Dr Conley’s note suggested that Mr Trump’s viral load was dropping, but still seemed detectable.
The subgenomic mRNA mentioned by Dr Conley is part of the virus that can be detected by laboratory techniques, suggesting the presence of an actively replicating virus, said Susan Butler-Wu, clinical microbiologist at the University of Southern California. But “there is no licensed test that examines the subgenomic mRNA” of the coronavirus, she added, meaning the procedure is “experimental at this point.”
Another, more traditional approach to determining whether Mr. Trump still harbored an actively replicating virus in his body could be to take a sample from the president’s airways and see if the coronavirus could be grown from the sample in a laboratory. But this technique was not mentioned in Dr. Conley’s memo.