Washington(CNN) President Donald Trump has been cleared to return to an active schedule, according to a new memo from his physician, Dr. Sean Conley, released Saturday night.
The memo says Trump has met criteria from the US Centers for Disease Control and Prevention to end isolation but does not say Trump has received a negative coronavirus test since first testing positive for the virus last week. However, that is not a criteria for clearing isolation, according to the CDC.
"This evening I am happy to report that in addition to the President meeting CDC criteria for the safe discontinuation of isolation, this morning's COVID PCR sample demonstrates, by currently recognized standards, he is no longer considered a transmission risk to others," the memo from Conley reads in part.
Conley wrote that Trump is 10 days from the onset of symptoms, has been fever-free for "well over 24 hours" and after diagnostic tests, "there is no longer evidence of actively replicating virus."
The President's doctor said Trump had undetectable "subgenomic mRNA." Those are molecules produced when viruses replicate. Their absence may suggest Trump is no longer shedding live virus.
But Conley did not fully explain what "advanced diagnostic tests" the President received. For example, he did not disclose whether so-called viral culture was performed. That's the process by which scientists try to infect living cells to see whether active virus is present.
According to CDC guidance, research has shown that PCR tests can still pick up pieces of genetic material from the virus long after someone has recovered. But these people aren't likely to be infectious 10-20 days after symptoms began. Even though PCR tests can come back positive, patients don't tend to be infectious after that 10-20 day window has passed, research has found.
The latest disclosure from Conley comes as Trump prepares to return to the campaign trail after being sidelined amid his fight with the virus. It's likely to raise additional questions about the health of the President as officials continue to provide carefully worded statements as the campaign enters its final stretch.
Trump on Saturday held his first public event since his diagnosis, delivering a highly political speech to a crowd of supporters packed on the White House's South Lawn. He is currently scheduled to hold at least three in-person rallies this upcoming week, beginning Monday in Florida. Conley says he will continue to monitor Trump "as he returns to an active schedule."
Officials -- including Conley -- still haven't disclosed when the President last tested negative before his positive test last week, which would offer insight into when he was contagious and how much so.
Trump, who left the hospital earlier this week after receiving treatment for the virus, credited his quick recovery to his rapid treatment during an interview with Fox News on Friday.
"I think the secret for me was I got there very early," he told the network's medical contributor Dr. Marc Siegel.
Trump had received an immediate dose of an experimental monoclonal antibody therapy at the White House, then was treated with a course of the infused antiviral medication remdesivir and the steroid dexamethasone during his hospital stay. He had also been given supplemental oxygen, Conley previously said.
This story has been updated with additional background information and context.