Weddings, a conference and a motorcycle rally eyed as COVID-19 superspreader events: Here's why experts say 'don't go' to large gatherings

The 80th Annual Sturgis Motorcycle Rally in Sturgis, South Dakota, which took place n early August, has been identified as a coronavirus superspreader event. (Photo by Michael Ciaglo/Getty Images)
The 80th Annual Sturgis Motorcycle Rally in Sturgis, South Dakota, which took place n early August, has been identified as a coronavirus superspreader event. (Photo by Michael Ciaglo/Getty Images)

An alarming new epidemiological study released Tuesday details how a business conference in late February was ultimately responsible for 20,000 cases of COVID-19. The conference, which the study’s researchers dubbed a “superspreading event,” may be one of the largest instances of viral spread since the pandemic began.

Done by scientists at the Broad Institute of Harvard and MIT, the study, which is a pre-print and hasn’t been peer-reviewed yet, traces the cases back to a conference held by drug company Biogen at a Boston hotel on Feb. 26 and 27. On the conference start date, there were just 15 confirmed cases of COVID-19 in the U.S., according to the Washington Post. By analyzing genomic data, the researchers found that the virus then spread to four counties in Massachusetts and was also responsible for a large outbreak in Boston’s homeless population.

“Our results highlight the failure of measures to prevent importation into Massachusetts early in the outbreak, underscore the role of superspreading in amplifying an outbreak in a major urban area, and lay a foundation for contact tracing informed by genetic data,” the study’s co-authors wrote.

The new study raises questions about COVID-19 and so-called superspreading events, or single gatherings that spark an outbreak of cases of the virus. Here are some of the biggest incidents that have been identified recently as superspreader events, and what we can learn from them.

February: Biogen conference, Boston, Mass.

In late February, Biogen hosted a conference at the Boston Marriott Long Wharf, a hotel that was later shut down in mid-March over COVID-19 concerns, according to the Boston Globe.

“February 2020 was nearly a half year ago, and was a period when general knowledge about the coronavirus was limited,” Biogen said in a statement to the Boston Herald. “We were adhering closely to the prevailing official guidelines. We never would have knowingly put anyone at risk. When we learned a number of our colleagues were ill, we did not know the cause was COVID-19, but we immediately notified public health authorities and took steps to limit the spread.”

“This is probably the biggest superspreading event in the pandemic,” Dr. Amesh A. Adalja, senior scholar at the Johns Hopkins Center for Health Security, tells Yahoo Life. The timing is important here, Adalja adds. “There weren’t really widespread guidelines on how to prevent the spread of the coronavirus at that point.” A conference like this is particularly concerning for the spread of the virus because “people have so many contacts and potential opportunities for spread in these situations,” Adalja says.

Video: Large gatherings impacting coronavirus totals

July: Wedding, San Francisco, Calif.

A large, covert wedding at San Francisco’s Saints Peter and Paul Church was shut down by the city attorney’s office as it defied local public health ordinances. An email obtained by NBC Bay Area showed that local authorities received a complaint about the planned wedding of 100 people that was happening with the knowledge of the pastor.

At the city attorney's request, the wedding was moved outside to a connecting basketball court. Still, the bride, groom and at least eight guests may have contracted COVID-19 there, the San Francisco Chronicle reports. People flew in from Nashville, Tenn., Arizona, and San Diego, Calif., for the wedding, per SF Gate, and 40 wedding guests celebrated on the outdoor patio the night before at the city’s Harborview Restaurant and Bar.

A guest later told the San Francisco Chronicle that no one wore masks at the rehearsal dinner and that social distancing was non-existent.

While the event has been linked to at least 10 cases of COVID-19, the actual number may be more, Schaffner says. “People can get infected in these events and then they disperse and take it back home with them,” he says. “It becomes very difficult to measure because, after the event, people spread out over large geographic areas. If they go back home and develop disease, you may not know about it. Meanwhile, they spread it further in their own communities.”

August: Wedding reception, Millinocket, Maine

On Aug. 17, the Maine Centers for Disease Control and Prevention revealed it was investigating a COVID-19 outbreak tied to a wedding reception at the Big Moose Inn in Millinocket, Maine. At the time, 24 people associated with the event had tested positive for the virus. About 65 guests attended the event, the Maine CDC said. As of now, at least 53 cases of COVID-19 and one death have been traced back to the event.

State requirements say the number of people who can gather at an event should be limited to 50 indoors and 100 outdoors, or fewer if the space can’t accommodate five people per 1,000 feet, the Maine CDC says.

Dr. Nirav Shah, director of the Maine CDC, said Tuesday during a news briefing that the wedding has now been tied to an outbreak of six cases at the state’s Maplecrest Rehabilitation & Living Center in Madison. The wedding is also linked to an outbreak of 18 cases at the state’s York County Jail, Shah said.

A man who stayed at the inn while the wedding took place told the Lewiston Sun Journal that the event was “very crowded” and that there was “not much social distancing.” He added, “I saw maybe one or two people wearing a mask, but that was it.”

Weddings are prime spots for the spread of COVID-19, Dr. William Schaffner, an infectious disease specialist and professor at the Vanderbilt University School of Medicine, tells Yahoo Life. “What usually happens is that many people are unmasked, maybe all of them,” he says. “People get close to each other and they’re often celebrating, dancing, and talking — and that can spread the virus.”

August: Sturgis Motorcycle Rally, Sturgis, South Dakota

State health departments have reported at least 103 cases of COVID-19 from people in South Dakota, Minnesota, Wisconsin Nebraska, Montana, North Dakota, Wyoming, and Washington who attended the 10-day Sturgis Motorcycle Rally in Sturgis, South Dakota, according to the Associated Press. Adalja says he expects that number to climb. Photos from the rally, which kicked off on Aug. 7, showed many bikers unmasked and not following social distancing guidelines.

South Dakota does not have a statewide mask ordinance and Gov. Kristi Noem, who said on Fox News that she was proud to have her state host the annual event, has spoken out against wearing masks in public.

The city of Sturgis is now conducting mass testing for its 7,000 residents, the AP reports, and an analysis of anonymous cell phone data from Camber Systems, a firm that aggregates cell phone activity for health researchers, found that attendees from the rally visited 61 percent of all the counties in the U.S. after the event.

“I am concerned about Sturgis because of the magnitude of exposure both in number and geographic reach,” Dr. David Cennimo, an infectious disease expert and assistant professor of medicine at Rutgers New Jersey Medical School, tells Yahoo Life.

But, Adalja says, it’s hardly shocking to see cases come out of the rally. “This was completely predictable,” he says. Still, he adds, it’s difficult to fully trace all cases that may come out of the event back to the rally due to the wide geographic spread of attendees after the event.

As a whole, larger events in the U.S. are “dangerous,” according to Dr. Richard Watkins, an infectious disease physician in Akron, Ohio, and a professor of internal medicine at the Northeast Ohio Medical University. “‘Don't go’ is the simplest advice,” he says. “Your health should be more important to you than a one-time event. COVID-19 can cause long-term damage to your body and people should take it very seriously.”

Schaffner agrees. “If there is an event, don’t go,” he says. “Large gatherings are not going to be recommended for some time.”

For the latest coronavirus news and updates, follow along at According to experts, people over 60 and those who are immunocompromised continue to be the most at risk. If you have questions, please reference the CDC’s and WHO’s resource guides.

Read more from Yahoo Life

Want lifestyle and wellness news delivered to your inbox? Sign up here for Yahoo Life’s newsletter.