President Donald Trump announced late Thursday night that he and his wife, Melania, have Covid-19. Several other people with connections to the presidency all got Covid-19 at about the same time, and that feels, intuitively, like a mystery. It should mean something—and not only for all those people’s mask-avoiding, crowd-embracing, pandemic-be-damneding behavior—but for the virus itself and how it is transmitted from person to person.
The question is, whodunnit? Or at least, how? How did the most powerful, most protected person on earth get infected with a pandemic disease that has killed over a million humans?
Epidemiologically, this could have been an example of the classic “household spread,” in which one person gives the disease to people they live with. Or maybe it was “community spread,” among people in casual contact—which has allowed the virus to bounce from neighborhood to neighborhood, city to city, nation to nation. Or was there a super-spreading event, a perfect-storm combination of conditions that make transmission more likely and one person who is somehow excellent at transmitting the disease?
Scientists increasingly think Covid-19’s main mode of transmission is as aerosols, infinitesimal blebs of virus-containing snot borne aloft on ever-present, gentle air currents. Come into contact with enough of that ill wind—for example you’re caught in a room full of it, or spend too much time too close to someone giving off those particles—and you get the disease. But no one knows how much is too much, or who is more likely to get infected, or to be more infectious. The virus spreads as an invisible vapor, but knowledge about it seems perpetually obscured by fog. It’s never easy to see what’s going on. And the case of the pandemic president hasn’t cleared it up. Like, at all.
The news has moved fast. It was only Thursday morning that Bloomberg reported that Trump’s close aide Hope Hicks was infected with Covid-19; she had traveled with the president to his debate with election opponent Joe Biden on Tuesday and to a large outdoor rally. The president suggested that Hicks had caught the disease from “people from the military and law enforcement” who keep wanting to hug him and his team. Hicks had been tested after showing symptoms; it turned out the president was symptomatic too. Hours later he was tested, and both he and his wife were positive. A day later, the president was helicoptered to Walter Reed Medical Center; his drug regimen includes a still-experimental antibody therapy.
So for a while it was easy to think that Hicks had been the vector. Maybe.
But perhaps the trickiest thing about Covid-19 is that between the time a person gets infected and when they start showing symptoms, they can still pass the virus along to others. That’s called the incubation period, and it can be as short as two days or as long as two weeks. “There were many moments during the last week when Trump’s infection could have occurred,” says Helen Jenkins, an epidemiologist at Boston University. “You can try to think carefully about: What’s the incubation period, the time from exposure to symptoms? There are distributions around these time periods, so you could try and get a sense of who may have infected whom and when infection may have happened. But given that they were together several times over the past few days, it would be difficult to pinpoint.”
In fact, Covid-19’s incubation period probably means that the president and his wife could have been infectious at the Cleveland debate with Biden. The former vice president has announced that he and his wife have tested negative for the disease, but, again, there’s that incubation period to worry about. Biden and the president were standing pretty close together. The president was bombastic, and yelling transmits viral particles better than speaking quietly. “It’s too early to say they’re in the clear,” says Tara Smith, an epidemiologist and infectious disease researcher at Ohio’s Kent State University.
Still: It’s probably not simple household spread. For one thing, all these people don’t actually live together. “I think it’s definitely not a classic case of household spread because it’s not a classic household,” says William Hanage, an infectious disease epidemiologist at the Harvard T. H. Chan School of Public Health. “The White House is a big house.”
On Friday afternoon the news shifted, and the evidence against household spread got stronger. Utah senator Mike Lee announced that he, too, was positive for Covid-19. So did John Jenkins, the president of Notre Dame University. So did Republican National Committee chair Ronna McDaniel. So did three journalists who cover the White House. What they all (except maybe one of the reporters) had in common with Hicks and the Trumps was a singular event: the announcement of the nomination of Amy Coney Barrett to the Supreme Court, in the Rose Garden of the White House. If that’s where they all got it, the announcement could have been one of those dangerous coincidences where perfect conditions for transmission of the disease come together with one of the 20 percent of individuals whose bodies are, for unknown reasons, really good at giving the virus to other people. “At the moment, seeing that there’s this common link of one event among these people points in the direction of that being potentially a super-spreading event. But I think we still need more information,” Jenkins says.
That’s going to be tough to get. Dozens of people attended that event, and there have been fundraisers (indoors, without masks or social distancing) and rallies before and since. “Were they all infected by a single highly infectious person on Saturday? It's possible. It's also possible there were multiple infected people at that event,” says Marm Kilpatrick, a professor of ecology and evolutionary biology at the University of California, Santa Cruz. “The pictures I've seen of the Barrett announcement show dozens, maybe low hundreds of people, almost none of them wearing masks, sitting elbow to elbow with each other, and talking, hugging, and interacting before and after.”
“It's easy to speculate,” Kilpatrick continues, “but one would need a huge amount of information and data. And even with all of it, it's unlikely one could make a strong case about who infected whom.”
It’s a little easier, though, to speculate about how it all happened. The White House isn’t just big, as Hanage says. When it comes to a virus like this one, it’s also porous.
Not only has the White House failed to implement an NBA-style bubble, Trump’s campaign for a second presidential term has pressed forward with an aggressive schedule, flying around the country to attend large events, many of them indoors, packed with throngs of maskless supporters. Such behavior flies in the face of what public health experts have been urging for months: Wear masks, avoid crowds, stay at least 6 feet away from people outside your household, open windows, don’t linger in poorly ventilated indoor spaces. Each behavioral adjustment chips away at the risk of catching and spreading the coronavirus. Layer enough protections on top of each other and it’s possible to drive that risk down—if not to zero, at least to something approaching it.
The White House’s strategy has, in contrast, focused on testing. Everyone in the president’s orbit reportedly is regularly screened for the virus (though the Daily Beast reports that implementation has been casual at best). Trump himself has said part of the reason he doesn’t wear a mask is because “everyone's tested” before they see him. But tests capture just a single snapshot in time, and they’re not infallible.
So it was no surprise to epidemiologists like Smith that this strategy failed. “We can’t test our way out of this. We can’t rely only on diagnostics to keep things under control,” Smith says. Tests can be wrong. They can miss that crucial window when people become contagious. And because up to a third of people who contract the virus may never show symptoms, some infected people never do get tested—but they can still infect others. That’s why Smith says we also need the basics: “Masking, limited gatherings, social distancing, all the things we’ve been urging from the beginning, that unfortunately the Trump administration has ignored or outright mischaracterized and minimized.”
This isn’t just speculation. In a study currently under review, Hanage and his collaborators describe a simulation that tested the idea that testing, by itself, is enough. They simulated a community raging with virus, and then they modeled what happened if you tested all the patients who walked through the door of a health care facility, rounded up the ones who tested positive, and limited their interactions with health care workers and other staff. They compared that approach to the widespread use of personal protective equipment—including face masks, face shields, goggles, gloves, and gowns—without testing. A third run of the sim combined the two strategies.
Bottom line, says Hanage: Testing alone wasn’t sufficient. The virus still got in, and it set off outbreaks when it did. ”But I don’t think we need a model to make the argument that it’s beneficial to reduce all the potential transmission routes if you really want to stop the virus from getting into your network,” he says.
So really, it’s not a surprise that the novel coronavirus has reached the president; it’s a surprise that it took this long. For the past few months, there has been a steady drip of coronavirus contagion at the edges of Trump World, but none of them have breached the inner sanctum. In May, two White House staffers tested positive, including Vice President Mike Pence’s press secretary. In July, Tomas Philipson, a top economic adviser, caught the coronavirus, along with two Trump campaign staff members and Herman Cain, who later died from the disease. In August, Kimberly Guilfoyle, Don Jr.’s girlfriend and a top fundraiser for the Trump campaign, contracted the coronavirus. Dozens of Secret Service agents assigned to protect the president and vice president also tested positive in July and August following rallies in Oklahoma and Florida. “The responsibility for this isn’t on any particular person,” says Smith. “It’s on the whole attitude toward prevention in the president’s circle, which has not been very scientific.”
Which means it’s been luck, more than science, that kept the president coronavirus-free for as long as he was. Most people who become infected don’t spread the virus to any other individuals. As Zeynep Tufekci wrote recently in The Atlantic, thinking in averages is not useful for this pathogen, because it tends to spread in clusters. One paper found that in Hong Kong, about 20 percent of people were responsible for 80 percent of transmission. Nearly 70 percent of cases didn’t infect a single other person. But the odds that you wind up exposed to a super-spreading event go up the fewer precautions you take.
“The majority of introductions of this virus are expected to go extinct of their own accord,” says Hanage. “But if you allow enough of them in, eventually one of them won’t.”
Other researchers can quantify this effect. How much the disease spreads broadly is a combination of household spread and community spread, goes the current thinking, with occasional super-spreading events spiking through the community spread. Adding all that together—well, the math is fancier than adding, but you get the idea—gives you an “effective reproduction number” (or Re) for Covid-19 that depends on all sorts of environmental conditions and the infectiousness of the people with the disease.
But when it comes to the president’s extended household, that math needs caveats. “It’s hard to say what Re is relevant here, given all the travel, and it’s hard to pin down the role of household versus community,” says Jessica Metcalf, a demographer at Princeton who studies infectious disease dynamics. “And if it’s community, without contact tracing, it’s hard to figure out if it’s super-spreading.”
Hanage adds, though, that the fact that both Donald and Melania Trump tested positive at the same time hints at simultaneous exposure to the same infectious person—more like a super-spreading event, perhaps. Was it the Barrett announcement? No one knows. If it was, that’d be weird, because current science says transmission is rarer outdoors, like in the Rose Garden. But recent reporting says there were also adjunct, indoor portions of the event. One of those might have been the room where it happened.
“I hope they recover, but from an epidemiological point of view, it’s kind of fascinating,” Jenkins says. “I’d love to see that contact-tracing data, a diagram of where everybody was sitting, who was wearing masks and who wasn’t, who went indoors.” And to really know what happened with any scientific certainty, you’d need to not just conduct serious contact tracing but also sequence the unique genome of the coronavirus inside each infected person. Using the few but distinctive mutations that arise with each new infection, it’s possible to trace its route from person to person. Maybe, she says, someone will write a journal article about it one day.
Of course, no one wants the president or anyone who works in government—public service, after all—to get sick (or worse) in the course of their duties. No matter what your politics, it’s frightening when the president of the United States gets helicoptered to Walter Reed Medical Center because he’s ill with a potentially deadly virus. But even if it’s pretty clear that the president himself wasn’t the main source of the infection here, he isn’t without blame. A recent study from the Cornell Alliance for Science tried to characterize the “infodemic” of mis- and disinformation about Covid-19, everything from the idea that masks don’t work to strange patent remedies and the foolish notion that the entire pandemic is a hoax. Among other findings, the Cornell researchers determined that fully 37 percent of the misinformation about Covid-19 swirling across the media comes directly from President Trump. All the measures his White House has failed to take, all the bluster and dismissing of the pandemic’s severity, all the claims that he understood science better than scientists—they led here, now, to this: a president on a helicopter, racing to a hospital, while a planet full of humans wait, and try not to get sick.