Just how many people could be infected as part of the Trump COVID-19 outbreak?

U.S. president Donald Trump has tested positive for the novel coronavirus. Just how many people could he have passed the virus on to?

Normally, contact tracers try to tally up a person's close contacts starting around two days before they first start showing symptoms. But when the person in question is the President of the United States, that list can get very large, very quickly, and contact tracing can become a nightmare. 

For instance, Trump attended around 15  events in various states, from the 2020 presidential debate to fundraisers and rallies over the past several days, The New York Times reported. And for at least some of that time, the virus was likely silently multiplying in his body. Seeing as he rarely wears a mask in public and continues to attend events that don't follow social distancing guidelines, he likely spread the virus to others, said George Rutherford, professor of epidemiology and biostatistics at the University of California, San Francisco. 

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In particular, the president would likely have been quite infectious Thursday (Oct. 1) when he flew to a private fundraiser at his Bedminster resort in New Jersey, Rutherford said. Though it's still a bit of a jump to say at this point, "it's possible that this fundraiser will turn into a superspreading event," Rutherford said. "He could've infected a lot of people." 

Contact tracing on steroids

Typically, when a person becomes infected with the novel coronavirus, contract tracers will call that person and create a list of people who they have interacted with long enough and close enough for the virus to have infected. The contact tracers will then call all of these potentially exposed people to alert them that they should self-quarantine and get a test in order to prevent further propagation of the virus.

But because Trump has recently interacted with so many people, including other top government officials, finding and connecting with all of his contacts would be a Herculean task. The normal entities may not be trusted or able to do the tracing. "I suspect they won't turn it over to the Washington D.C. health department," but maybe the Centers For Disease Control and Prevention (CDC) or the Secret Service will attempt the contact tracing for the president, Rutherford told Live Science. Contact tracers typically go back 48 hours from when a person starts showing symptoms to identify close contacts, or those who have been together for at least 15 minutes within 6 feet (1.8 meters) of each other, Rutherford said.

If a person is infected on Day 0, on average, that person tests positive on Day 3, they become infectious on Day 4, develop symptoms on Day 5 and remain the most infectious (the body has the highest viral load) until about day 7 or 8, Rutherford said. 

The infection timeline

"If the president is indeed getting tested every single day, which is what we hear, that means he would have tested negative on Monday, Tuesday [and] Wednesday," before testing positive on Thursday (Oct. 1), Rutherford said. 

Trump and Melania were tested for the virus after news that Trump's close aide Hope Hicks tested positive for the virus, Live Science reported. Hicks had recently traveled with Trump aboard Air Force One to the presidential debate in Cleveland on Tuesday (Sept. 29) and to a Minnesota rally on Wednesday (Sept. 30). 

Trump is experiencing "mild symptoms," the White House chief of staff Mark Meadows told reporters today (Oct. 2). But Trump is expected to be taken to Walter Reed Medical Center this afternoon "out of an abundance of caution,"  administration officials said, according to The Washington Post.

If you give it 12 hours between the time he tested positive on Thursday night and developed symptoms, "he's probably in Day 5 of illness now," Rutherford told Live Science. That likely means that he would've been infected by the virus on Monday, he said. Other estimates place the exposure date as sometime between last Saturday and Monday, according to Buzzfeed News. On Saturday (Sept. 26), Trump announced Judge Amy Coney Barrett as his Supreme Court Nominee at a huge White House Rose Garden event where many attendees did not wear a mask.

But of course, these are average numbers and these timelines can differ. Also, "this is all kind of predicated on the thought that he tested negative," on all these days, Rutherford said. "They may not be testing him every day in which case all of this gets rejumbled." In July, Trump said he was typically being tested every two to three days, according to CNN.

On Monday (Sept. 28), Trump attended an event on the White House South Lawn surveying a Lordstown Motors truck along with two Congress members and three representatives from the company, according to his schedule published by The Associated Press. He also held an event in the Rose Garden, attended by many officials, to announce the distribution of millions of coronavirus tests to states.

That means that Trump could have been infected before the 2020 presidential debate with Joe Biden on Tuesday, but probably didn't have enough viral load to test positive. What's more, some of Trump's close aides said they sensed Trump wasn't feeling well and seemed exhausted on Wednesday, according to Bloomberg. That would push back the timeline and could mean he was infectious during the debate, according to The Atlantic.

What's more, the debate moderator and Fox News anchor Chris Wallace said Friday on Fox News that the candidates' negative test results were based on an "honor system" because they were tested by their own campaigns rather than by the clinic and reported the results as negative, according to Newsweek.

Who has been infected?

To control the outbreak, contact tracers need to ask who infected the president, who else that person may have exposed, and who else the president might have exposed, Rutherford said. 

One of the top priority events to investigate is the Bedminster fundraiser, because Trump was clearly infectious at that time, Rutherford said. Because it's a fundraiser, it would probably be easy for contact tracers to obtain a list of who attended, he added. (NJ.com is reporting that as many as 300 people attended that event.) 

In addition to guest lists for this and other events, contact tracers will also need a list of people who flew with Trump to events throughout the week.

If we aren't assuming Trump had a negative test on Wednesday, but rather working with the fact that he had a positive test on Thursday and developed symptoms later that night, you'd likely have to go back further. Along with the rally in Duluth, Minnesota on Wednesday, Trump also attended a private home fundraiser in Minneapolis, according to The Associated Press.

There are already a number of people in Trump's close circle, or who have attended events with Trump, who have announced testing positive for the virus. In addition to Hope Hicks, Sen. Mike Lee and the University of Notre Dame's president, Rev. John I. Jenkins, both tested positive for the coronavirus. Both attended the White House event for Judge Amy Coney Barrett last Saturday (Sept. 26). The number of infected people surrounding Trump may well grow in the coming days, as more positive tests roll in. In addition, a memo from the White House Correspondents' Association revealed that a White House staffer who sits in the "lower press" area received a positive coronavirus test result, a journalist received a "preliminary positive" result and a journalist who was last at the White House on Saturday and traveled on Air Force One to the Pennsylvania rally that night tested positive today, according to  tweets from CNN's chief media correspondent Brian Stelter.

A number of the president's close contacts  have also announced preliminary negative test results, including former Vice President Joe Biden and his wife, Jill Biden, Vice President Mike Pence and his wife, Treasury Secretary Steven Mnuchin, Secretary of State Mike Pompeo, Attorney General William Barr, Ivanka Trump and Jared Kushner. Speaker of the House Nancy Pelosi, Senator Dianne Feinstein and former New Jersey Governor Chris Christie are still awaiting results of their COVID-19 tests, according to news reports.

But negative test results don't necessarily mean a person is not infected; it may just be that the virus hasn't multiplied in the body enough to show up on tests. The Republican National Committee Chair Ronna McDaniel has also tested positive for the coronavirus. McDaniel, who frequently interacts with Trump and other top Republican officials, was last with Trump last Friday (Sept. 25), according to CNN. It's not clear how she was infected but she was tested for the virus after a family member tested positive for COVID-19 and has been quarantining at home since last Saturday (Sept. 26), RNC spokesman Mike Reed said in a statement.

The president, who is in a high-risk group for getting severe COVID-19 due to his age, has repeatedly downplayed the severity of the pandemic. Now that it's personal, will he adopt a different attitude? 

Originally published on Live Science.