As the cluster of coronavirus cases linked to the White House and Washington Republicans grows — there have been 12 reported so far, by Vox’s count — and it becomes increasingly apparent that most of the people with confirmed infections attended a recent White House reception for Supreme Court nominee Amy Coney Barrett, it’s reasonable to ask: Was this a superspreading event, meaning one where a lot of people get infected at the same time, by a common source?
It is difficult to say for sure, but that reception is a vivid example of what not to do during the Covid-19 pandemic:
From tomorrow’s NYT A1, a reminder that the Amy Coney Barrett WH event was not entirely outdoors pic.twitter.com/wSJvKOY4JD— Rebecca Buck (@RebeccaBuck) October 3, 2020
This picture, taken last Saturday at the White House, shows President Donald Trump hosting a reception for Barrett after he formally nominated her to the Supreme Court. There are so many pandemic-prevention red flags that jump out in this image: many people crowded together, indoors, with no open window in sight, talking and breathing without masks on.
“We don’t know that it’s a superspreader event for sure, but it certainly has all the makings of one,” Joseph Allen, a public health researcher at Harvard, says. “When you have large numbers of people spending time in close contact, unmasked, and indoors, it’s a recipe for superspreading.”
Superspreading doesn’t have a specific scientific definition. But, roughly, it’s defined as when one case of a disease causes a disproportionate number of others. It’s thought that much of the viral transmission of SARS-CoV-2, the virus that causes Covid-19, is due to superspreading. Most people with the virus actually do not pass it on to others. “Ten to 20 percent of infected people may be responsible for as much as 80 to 90 percent of transmission,” Zeynep Tufekci writes in the Atlantic in an overview of the latest research.
Superspreaders are made at the intersection of timing (a person is most contagious when their viral load peaks, usually right as they are starting to feel symptoms, or perhaps a bit before), an individual’s biology (some people may be predisposed to spread more than others), the activity (the longer the time spent with a superspreader, the greater the chances of being exposed to the virus), and the environment (indoor environments are much more conducive to allowing viral-laden aerosols to linger in a space longer, infecting more people).
All of these elements could have been in play at the White House event Saturday, which took place both outdoors and indoors, per reports. Beyond these factors, the event had another ingredient that might have been key in aiding the spread of the virus: a cavalier attitude.
“Attendees were so confident that the contagion would not invade their seemingly safe space at the White House that, according to [attendee Rev. John I. Jenkins, the president of the University of Notre Dame], after guests tested negative that day they were instructed they no longer needed to cover their faces,” the Washington Post reports of the event. “The no-mask mantra applied indoors as well. Cabinet members, senators, Barrett family members and others mixed unencumbered at tightly packed, indoor receptions in the White House’s Diplomatic Room and Cabinet Room.”
Epidemiologists see some telltale superspreading clues at the White House event
Allen points to Jenkins, the president of Notre Dame, as being a key clue in favor of this being a superspreading event. Jenkins tested positive for the virus the week after the gathering. But there is a key difference in his positive case compared to those of the lawmakers: He flew in to the event from out of town.
Many of the other guests at the White House “all operate in the same social and political circles,” Allen says, which makes it difficult to say whether they all got infected at this one event. “It’s very possible they could have gotten it sometime other than Saturday. But the fact that the president of Notre Dame was there and flew in and out adds some evidence, or certainly raises our suspicion, that this was an important event for the spread of the virus.”
Ideally, the White House will be testing and keeping in contact with every attendee of the reception. “If more and more cases are linked [to the event], then that adds a lot of evidence,” Allen says.
“The fact that everybody’s testing positive at the same time, developing symptoms around a similar time, suggests that, at the very least, there’s a shared source or a couple sources on too many of these infections,” Justin Lessler, a Johns Hopkins University epidemiologist, says.
But it’s doubtful we’ll find a specific smoking gun
More evidence could paint a clearer picture.
For instance: If a contact tracing investigation found out that the people who went inside during the event were more likely to get sick after, that would lend credence to the hypothesis that the Barrett gathering was a superspreader event.
We know that indoor environments are riskier than outdoor environments. If more people who attended the indoor portion of the event got sick than did for the outdoor portion, it makes the case for superspreading. Possibly, too, contact tracers could do genetic sequencing of viral samples obtained from attendees. If the viruses have a very similar genetic signature, then that’s also evidence that the event was the source of the outbreak.
But even with contact tracing, it might be difficult to pinpoint the exact source of the outbreak. “I doubt we’ll ever find a smoking gun,” Lessler says. It’s just really hard to know who came into the event already carrying the virus. There were dozens of people in attendance, and they all tested negative for the virus before attending. One or more of those guests could have been a false negative, which are common, particularly in the days before a person starts feeling symptoms of the illness.
This goes to show that frequent testing can help stop a burgeoning outbreak in its tracks, but it can’t stop some infections from occurring in the first place. Masking and social distancing are still crucial in stopping the spread of the virus.
Generally, people exposed to the virus start to feel symptoms after five days, but it could take 10 days or more for the virus to incubate. So if more people were exposed to the virus at this White House event, we’d expect the last of them to start showing symptoms by now, or soon. What’s important now is to figure out if there were any secondary chains of infections caused by attendees.
“We’re definitely in the incubation period for any secondary contact,” Allen says. If people who contracted Covid-19 at the reception went elsewhere, met other people, and had the same lax attitude toward masking and distancing, then there may be more infections to come from this cluster, too. And remember: We may hear about high-profile people like former White House adviser Kellyanne Conway falling ill with the virus, but maybe not about their staff or people they interact with day-to-day.
Even if we never know the role this White House reception played in the outbreak, we can take it as a clear example of what not to do. Events like these are “fertile ground for a superspreading type event to happen, whether or not one did,” Lessler says. “These gatherings of a lot of people, they can really amplify the epidemic.”