Medical Examiner

What Are the Chances Trump Gave Biden COVID-19 at the Debate?

Update: Biden has tested negative. That doesn’t mean he’s in the clear.

Donald Trump and Joe Biden stand beside their podiums on the stage
Donald Trump and Joe Biden at the debate Tuesday night. Win McNamee/Getty Images

Update, Oct. 2, 2020, at 4:23 p.m.: Biden has tested negative, but it can take several days for the virus to show up in a test.

Could Donald Trump have given Joe Biden the coronavirus during Tuesday night’s debate? Let’s go down this speculative rabbit hole together.

It’s hard to say whether Trump was contagious at the time of the debate—we’ll get to that part more in a moment. But if Trump was contagious at the debate, could he have directly spread the virus to Biden? The podiums were more than 6 feet away from each other, which is a good precaution. And for all the chaos at the debate, the two were using microphones, not screaming across the stage, which could cut down on the production of particles. Still, a main reason that the pandemic is so tough to control—and the reason masks are so important—is that an infected person who is showing no signs of being infected can expel floaty coronavirus-laden particles simply by breathing. This means that distancing isn’t necessarily enough indoors, especially when people are together for a prolonged period of time.

The risk to Biden on the stage itself from a potentially infected Trump is “really going to depend on the ventilation in the room, and the air purification,” says Angela Rasmussen, a virologist at Columbia University. It’s hard to tell what that was, sitting at home watching on television. There were no obvious open windows in the atrium, and no hum of heating, ventilating, and air conditioning systems muddling the audio. But since the debate took place in a space that was this spring set up as an emergency hospital, we can assume that the folks at the Cleveland Clinic—one of whom was reportedly trying to pass out masks to the Trump family as they sat to watch that whole shitshow with bare faces—put some thought into the airflow dynamics here.

So … could Trump have been contagious at the debate? Everyone who attended was tested first, so if Trump received a negative test Tuesday—likely—that lowers the chances somewhat. In general, if you don’t have enough virus in you to test positive, you’re less likely to be contagious. But a lot depends on the type of test. We don’t know what kind of test he took, but we do know that the rapid test the White House sometimes uses has been reported to miss half of infections. Still, a false negative is a possibility no matter the test. It also matters when in the day he got tested. If the test was that morning, “it’s completely possible that by the time the debate came around in the evening, he could be potentially contagious,” says Rasmussen. “There’s just a lot of variables.”

It’s somewhat safe to assume that Trump had been tested between the debate Tuesday night and his positive test Thursday night. Press secretary Kayleigh McEnany has previously claimed that “the president is the most tested man in America,” with tests sometimes more than once a day. Even if that’s an exaggeration, it’s reasonable that an actively campaigning president of the United States would be tested daily. Is it reasonable to assume that Trump would announce a positive test, if he had one on Wednesday or Thursday morning? That’s harder to say—Bloomberg News, not the White House, broke the news that Hope Hicks had tested positive. There’s speculation that he was showing symptoms earlier in the week—was a Wednesday night nap on Air Force One due to COVID-19? If that was truly a symptom, it could mean he was contagious Tuesday, according to Centers for Disease Control and Prevention recommendations.

Even if he wasn’t, “the debate itself is not the only opportunity for the virus to spread,” says Rasmussen. The first thing that happened after the debate was Melania Trump walking onto the stage maskless. Was there any mingling, or near-mingling, among Trump family members and Biden family members? If the Biden camp was being careful—they were wearing masks during the debate—maybe not. But surely some mutual contacts have to interact, at least a little bit, in the course of putting on a televised event. Even among people who are being careful, masks aren’t foolproof. Who among the Trump camp may have been infected, and in turn interacted with the Biden camp, with what precautions, is difficult to speculate about. But we do know that the virus likes to spread among people, particularly when people have been indoors together for long periods. “I think there is a possibility for there to be a rather large outbreak within the White House, within the campaign,” says Rasmussen. Even if Trump wasn’t infected on Tuesday night, “presumably, other people in that circle might be.” It seems like transmission among mutual contacts—which is a big question mark—would be more likely than direct transmission on the stage.

How likely is it that Biden is infected via Trump? “The most quantitative I can get about it is to say the risk is not zero,” says Rasmussen.

Joe Biden will get a test this morning.