Was Trump's Indoor Rally a Superspreader Event?

Caroline Delbert
·6 min read
Photo credit: Ethan Miller - Getty Images
Photo credit: Ethan Miller - Getty Images

From Popular Mechanics

Before his campaign rally in front of thousands at a manufacturing plant in Henderson, Nevada on Sunday, President Donald Trump told a Nevada newspaper that he was exempt from Gov. Steve Sisolak's law limiting indoor gatherings to 50 people due to COVID-19 concerns. “I’m on a stage and it’s very far away,” Trump told the Las Vegas Review-Journal. “And so I’m not at all concerned.”

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Trump’s comments signal his belief that maintaining distance is important in slowing the spread of COVID-19; in the same Review-Journal interview, he criticized a reporter for not staying far enough away. Coverage of Trump's indoor rally, however, which the president says drew 5,000 attendees, has mentioned the idea of “superspreader” events, where it takes just one person to infect many others.

While many of Trump’s supporters sat close together on white folding chairs, and face masks were only required for the attendees directly behind the president in the television shot, per the Washington Post, it’s too soon to tell if the Nevada rally was indeed a superspreader event. And the research on such events at this juncture is still inconclusive: A non-peer-reviewed research paper tied last month’s massive Sturgis Motorcycle Rally in South Dakota to 250,000 new COVID-19 cases, but even Snopes says that claim is unproven.

But one real superspreader event we can examine is a small wedding held in Maine in August. The Boston Globe reported on the wedding, where “few of the 62 wedding and reception attendees wore masks.” The small town of Millinocket had zero recorded cases of COVID-19 before this wedding. After the event, everything changed.

The Globe reports:

“An unidentified wedding guest reported feeling symptoms a day after the ceremony. Within four days, several others fell ill, according to state authorities. In all, nearly half of the attendees, 30 in all who ranged in age from 4 to 78 years old, would test positive.”

By the time the Globe published its feature late last month, Maine’s health officials had linked 123 cases directly to the wedding, which also violated Maine’s law limiting gathering size during the pandemic.

The Centers for Disease Control and Prevention (CDC) covers superspreader events (SSEs) in detail, including factors that increase risk of a situation becoming an SSE. It’s rarely as simple as one person coughing a brand-new virus on another person, the CDC explains:

“SSEs are not limited to emerging infectious diseases. In the early 20th century, Mary Mallon (Typhoid Mary), an asymptomatic typhoid carrier who worked as a cook, infected >50 persons. [Many tuberculosis patients,] even those with smear-positive, cavitary tuberculosis, were not highly infectious but 3 of 77 patients accounted for 73% of the infectious burden.”

At the Maine wedding, the hosts officially took temperatures of all the guests, which rules out certain kinds of symptomatic carriers. Scientists and mainstream press have debated the role of “asymptomatic carriers” in the pandemic, but it’s likely an asymptomatic carrier infected others in the wedding group.

“Environmental factors include population density and the availability and use of infection prevention and control measures in healthcare facilities,” the CDC explains. “Behavioral factors include cough hygiene, social customs, health-seeking behavior, and adherence to public health guidance.”

Social customs are crucial here. In 2010, researchers wrote about how students graduating from a university insisted on shaking hands despite the H1N1 pandemic at the time. “A graduation is a socially significant gathering and a ritually charged ceremony marking a personally and socially important transition,” those researchers wrote. And as handshakes are to graduation, hugs and dancing are to weddings.

Photo credit: Ethan Miller - Getty Images
Photo credit: Ethan Miller - Getty Images

A political rally doesn’t (usually) involve people dancing while facing each other. The risk factors are different, and it doesn’t make sense to fully translate the nearly 50 percent infection rate of the wedding to such a different kind of event. People are standing or sitting and facing the same direction while they watch. They might be yelling, but they’re not puffing that vapor directly into other people’s faces.

Let’s find a better comparison point: an airline-sponsored study of infection rates aboard airplanes from 2018. That study used an example flight “in 1977, in which 38 of 54 passengers and crew became infected with influenza-like illness after waiting in an airplane on an airport tarmac for 4.5 [hours] with no air circulation.”

That sounds like a nightmare scenario even without a pandemic. The study found, logically, that the people directly around an infected person, within 1 meter in any direction, were most likely to be infected.

In Nevada, there are 2,431 cases per 100,000 residents, according to CDC numbers updated through September 14. If 5,000 people attended Trump’s indoor rally, and the crowd was indeed limited by the size of the venue, we can extrapolate both that it was fairly crowded, and that the crowd broadly reflected Nevada’s overall infection rate.

That means there were about 122 infected people in the group. If each of them is standing in a typical gridlike crowd arrangement, they’re within 1 meter of about eight others—think of Alice in the center square of the Brady Bunch. That means, hypothetically, nearly 1,000 people were exposed to the coronavirus during the event. And there’s a catch-22 with wearing masks, because people who believe masks aren’t effective are unlikely to wear them even to indoor events, which then doesn’t afford an opportunity to see how effective they are.

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Let’s say, generously, that half of the carriers wore masks and half of the eight people around each carrier wore masks. That means instead of 1,000 people in the zone, we have four people each around each of about 61 carriers, which is still nearly 250 people. (In firsthand footage from a recent Trump rally, only a few people even have masks hanging around their necks, and no one is wearing a mask as recommended.)

Photo credit: Ethan Miller - Getty Images
Photo credit: Ethan Miller - Getty Images

Going back to the CDC’s guidance about SSEs, conditions around this rally are not good. Henderson, where the rally was held, is a suburb of Las Vegas, which is densely populated to begin with and also host to a constant stream of tourists. “Behavioral factors” like “adherence to public health guidance” are flouted even in the video and by Trump’s own comments.

Guests from the wedding in Maine brought infection into their small towns and even to high-risk elderly people who had sheltered in place for the entire pandemic. If even a few people from a large indoor rally are exposed to COVID-19, the effect could multiply out very quickly.

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