Trump's upcoming campaign rally could be the US's next coronavirus superspreading hot spot

• President Trump will hold his first campaign rally in months on June 20 at Tulsa, Oklahoma's BOK Center — an indoor arena that fits more than 19,000 people.
• Before registering, rally participants have been asked to sign a waiver and "assume all risks related to exposure to COVID-19" before attending.
• Research suggests large, indoor gatherings, like the upcoming rally, are responsible for most coronavirus transmission.
• While an average person with the coronavirus infects about two other people, an infected person can sometimes pass the virus to far more people during such gatherings: This is called a superspreader event.

President Donald Trump is back on the campaign trail, and his impending indoor rally could exacerbate the spread of the coronavirus.

The president announced that he would be holding his first Make America Great Again rally in four months on June 20 at Tulsa's BOK Center, an indoor sports arena and concert venue that can seat more than 19,000 people.

But according to public health experts, large, indoor gatherings like the upcoming rally are the sites of coronavirus superspreader events, in which a small number of individuals infect a disproportionately large number of other people.

"This virus really likes people being indoors in an enclosed space for prolonged periods of close face-to-face contact," William Schaffner, a professor of preventive medicine at Vanderbilt University, previously told Business Insider. "You can't have a superspreading event unless there are a lot of people around, so you have to be very careful still about gatherings of people of any size."

As many as 20,000 people flocked to Trump's MAGA rally on February 20 in Colorado Springs — just weeks before the US started locking down public spaces due to the coronavirus pandemic.

And Trump's upcoming rally — with "ticket requests in excess of 200,000 people" — is likely to be just as crowded.

He tweeted that other MAGA rallies would soon be coming to Arizona and North Carolina, and part of the Republican National Committee's convention, in which Trump will accept his party's nomination as the 2020 presidential candidate, is slated for late August in Jacksonville.

RNC officials reported they anticipated 50,000 people would attend the convention.

Rally attendees have to sign a waiver acknowledging coronavirus transmission risk

Current CDC guidelines encourage event organizers "to prepare for the possibility of outbreaks in their communities" following mass gatherings.

The agency recommends social distancing and wearing cloth face coverings and when talking, singing, and shouting to reduce transmission risk.

"The guidelines, really I think, speak for themselves," Jay Butler, deputy director for infectious diseases at the CDC, said in a press briefing Friday. "They are not commands, but they are recommendations or even suggestions ... of how you can have a gathering that will keep people as safe as possible."

But it's unlikely either recommendation will be implemented during the rally, Trump campaign officials familiar with the decision-making process told The New York Times.

Instead, rally attendees are being asked to sign a waiver before registering for the event that prevents them from suing the Trump campaign or BOK Center should they contract the coronavirus.

"By clicking register below, you are acknowledging that an inherent risk of exposure to COVID-19 exists in any public place where people are present," the disclaimer notes.

But that waiver doesn't prevent the virus from spreading if an infected person attends the rally

Oklahoma is in phase-three of its re-opening plan, which stipulates citizens should minimize time spent in crowded environments and continue following CDC guidelines regarding social distancing.

But Trump's rally may not abide by either of those stipulations.

The rally falls under the CDC's "highest risk" category for gatherings: "Large in-person gatherings where it is difficult for individuals to remain spaced at least 6 feet apart and attendees travel from outside the local area."

Republicans from across the country may flock to the rally, and those arriving on flights from the New York tri-state area, Washington state, California, or Louisiana will not be able to abide by Oklahoma Gov. Kevin Stitt's executive order that they quarantine for 14 days, considering Trump announced the rally on Wednesday.

And even though attendees are willing participants in a high-risk activity, those waivers they sign do not protect others that they come in contact with after the rally (their elderly family members, their neighbors, the people they may cross paths with at a restaurant) — who signed no such waiver.

Plus, Trump's rally comes at a time when coronavirus cases are already rising in nearly half of all US states.

"We know the pandemic is not over," Butler said, adding that "the vast majority of Americans still have not been exposed to this virus."

Superspreading events occur when large groups of people gather indoors

The fact that the rally is happening inside further exacerbates the risk of coronavirus transmission and makes the event a likely location for a coronavirus superspreader event.

So far, these events have all shared a few key characteristics: They've involved indoor gatherings in which a lot of people from different households were in close, extended contact.

In that sense, it's not that certain "super spreaders" are more contagious than others or shed more virus. Instead, there's a type of activity that gives people access to a greater number of people in areas conducive to the virus' spread, Ben Cowling, an epidemiologist from Hong Kong previously told Business Insider.

A South Korean churchgoer infected 43 others in February, a singer infected 53 people at a choir practice in Washington a month later, and a pastor and his wife spread the virus to 92 people they came into contact with at their Arkansas church.

Research has found time and again that the risk of coronavirus transmission is higher indoors in poorly ventilated spaces where lots of people have sustained contact. That's because it primarily spreads via droplets that fly through the air when an infected person coughs or sneezes.

A recent study found that even talking loudly can produce enough droplets to transmit the coronavirus and that those droplets could linger in the air for at least eight minutes. Vigorous singing, too, has been linked to the virus' spread because it can send infectious droplets farther than the recommended 6 feet of social distancing.

Several performers have canceled or postponed their upcoming summer concerts at the BOK Center.

And superspreader events are the primary means by which the coronavirus spreads, a recent study suggested.

In fact, 20% of cases caused 80% of transmissions in Hong Kong, China — a majority of which were linked to superspreading events at a wedding, temple, and multiple bars.

"If we could stop the superspreading from happening, we'd benefit the most people," Cowling said.

Hilary Brueck and Rosie Perper contributed reporting to this story.