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Do More Crowds Mean More COVID-19 Cases? It Depends on the Event

crowd in masks

 

Miguel Pereira / Getty Images

Key Takeaways

  • Public health officials warn that being in a crowd can increase your risk of COVID-19, but not all crowds have caused outbreaks.
  • Factors like whether an event is held outdoors and if people are wearing masks matter, experts say.

In the fight against COVID-19, crowds have been enemy No. 1. After all, social distancing is one of the key methods of preventing the spread of the virus. But crowds can and do happen—and they haven’t always been predictive of the spread of the virus.

Some crowded events, like Black Lives Matter protests in Minneapolis and New York City, don’t appear to be tied to any major outbreaks of COVID-19. But an indoor political rally in Tulsa, Oklahoma, for President Trump has been linked to a spike in cases.

It’s understandable that people might be confused about crowds. Experts say that it’s important to keep in mind that crowds can be sources of transmission, even if transmission doesn't always occur.

“What happens in those crowds and how people behave matters,” Peter Winkelstein, MD, professor and executive director at the Institute for Healthcare Informatics at the University at Buffalo, tells Verywell.

What This Means For You

Going into any crowd—indoors or outdoors—raises your risk of contracting COVID-19. And, while some gatherings haven’t been linked with an increase in cases of the virus, that doesn’t mean it can’t happen. Experts think it's best to play it safe and steer clear.

Why Crowds Are Conducive to COVID-19 Spread

Based on what we know about COVID-19, crowds, in theory, would be hot spots for viral transmission. According to the Centers for Disease Control and Prevention (CDC), the virus is thought to spread mainly between people who are in close contact with each other, specifically through respiratory droplets produced when an infected person coughs, sneezes, or talks. Those droplets can land in the mouths or noses of people who are nearby or possibly be inhaled into the lungs, infecting them as well.

There is some evidence that COVID-19 may also be an airborne virus, meaning it can linger in the air. However, that's still being explored. The World Health Organization (WHO) held a press conference in early July, stating "the possibility of airborne transmission in public settings, especially in very specific conditions of crowded, closed, poorly-ventilated settings cannot be ruled out."

While major medical organizations, including the WHO and CDC, haven’t taken an official stance on this yet, the WHO has updated its information about COVID-19 transmission to encourage people to "avoid crowded places, close-contact settings, and confined and enclosed spaces with poor ventilation."

The CDC also stresses that COVID-19 may be spread by people who are not showing symptoms.

How Likely Are Certain Crowded Events to Spread COVID-19?

In general, certain crowds may be riskier than others.

Protests

Despite predictions from public health officials, Black Lives Matter protests have not been linked to a spike in COVID-19 cases. A study published by the National Bureau of Economic Research in June analyzed data on protests from more than 300 of the largest U.S. cities, and found there was no evidence of COVID-19 surges in the weeks after the start of the protests.

Protesters march at a Black Lives Matter protest in Washington Square Park on July 12
Protesters march at a Black Lives Matter protest in New York City's Washington Square Park on July 12.  

“I was surprised,” David Cennimo, MD, assistant professor of medicine at Rutgers New Jersey Medical School, tells Verywell. However, he says certain factors, like many protesters wearing masks and the protests being held outdoors, likely helped. “We have seen increasing data that indoor activities pose significantly added risk,” he says.

Political Rallies

President Trump held an indoor political rally in Tulsa, Oklahoma, on June 20, which drew 6,200 people, according to The New York Times. The rally has been linked to a surge in cases.The Tulsa Health Department reported 261 new confirmed cases on Monday, July 6, more than two weeks after the rally was held.

President Trump hosts a rally in Tulsa, Okla., on June 20
President Trump hosts a rally in Tulsa, Okla., on June 20.  Win McNamee / Getty Images

“The past two days we’ve had almost 500 cases, and we know we had several large events a little over two weeks ago, which is about right,” Tulsa Health Department Executive Director Bruce Dart said at a news conference on July 9. “So I guess we just connect the dots.”

Dart also noted that the county has more infections than any other county in Oklahoma and “we’ve had some significant events in the past few weeks that more than likely contributed to that.”

Oklahoma Governor Kevin Stitt recently announced that he tested positive for COVID-19, weeks after attending the rally. 

Many photos from the event show people who were not wearing masks—including Stitt.

“Being close to a large group of people without social distancing or mask use still poses significant transmission risk,” Prathit Kulkarni ,MD, an assistant professor of medicine in infectious diseases at the Baylor College of Medicine, tells Verywell. “Even with mask use, appropriate social distancing is still recommended to minimize risk as much as possible.”

Sporting Events

NASCAR held a race at Bristol Motor Speedway in Tennessee last week, drawing 20,000 fans. Photos from the race show many fans without face masks who are close together. That kind of setting can easily allow the virus to spread, Winkelstein says.

Crowds in the stands of the Bristol Motor Speedway on July 15
Crowds in the stands of the Bristol Motor Speedway on July 15. Patrick Smith / Getty Images

“If you’re outside, spread out at least 6 feet apart, watching a sporting event and sitting quietly, that’s pretty safe,” he says. “But if you’re all packed together in the stands, screaming and yelling, that is not so safe.”

Winkelstein also expressed concerns about concession stands at all sporting events, given that people would have to take their masks off.

Concerts

The potential for outbreaks tied to indoor concerts is huge, Winkelstein says. “People packed together indoors, singing and yelling together…that, in my opinion, would be a disaster,” he says.

Research has specifically linked singing with outbreaks of the virus. Data released by the CDC found that, after a 2.5 hour choir practice in Washington state with one symptomatic person in May, 87% of the choir group became infected. Three people in the group were hospitalized after contracting the virus and two died.

“Transmission was likely facilitated by close proximity (within six feet) during practice and augmented by the act of singing,” the CDC says in the report.

How Have Some Crowds Avoided Outbreaks?

There are a lot of factors that go into how risky a crowd is—and how likely a gathering is to cause an outbreak of COVID-19. The CDC specifically breaks down level of risk based on the type of gathering:

  • Lowest risk: Virtual activities, events, and gatherings.
  • More risk: Smaller outdoor and in-person gatherings where people from different households stay at least six feet apart, wear cloth face coverings, do not share objects, and come from the same local community, town, city, or county.
  • Higher risk: Medium-sized, in-person gatherings that allow people to stay six feet apart, with people coming from outside the local area.
  • Highest risk: Large in-person gatherings where it is difficult for people to remain spaced at least six feet apart and attendees travel from outside the local area.

Research has also suggested that wearing masks can help prevent transmission. A case report released by the CDC showed that, among 139 clients who were exposed to two hair stylists with COVID-19, no one contracted the virus. The stylists and clients all wore masks, the CDC notes.

“Adherence to the community’s and company’s face-covering policy likely mitigated spread of SARS-CoV-2,” the report says.

While the report refers to much smaller groups, Cennimo says that the data can also be applied to crowds. “The more spread out and the more masks, the less chance of infection,” he says.

Kulkarni agrees. “The main determinants of increased [COVID-19] cases after events with large crowds will be related to social distancing and mask use,” he tells Verywell. “The size of the crowd also impacts the growth in cases that might be seen after such an event.”

What Are the Official Recommendations About Crowds?

The CDC specifically recommends avoiding close contact with people outside your household to prevent the spread of COVID-19. That includes keeping six feet between yourself and others, something that can be difficult to achieve in a crowd, Winkelstein says. And, when physical distancing is difficult, the CDC recommends wearing a cloth face mask.

While the CDC doesn’t encourage people to gather in groups, the organization acknowledges online that some people may wish to do this. The CDC issued “guiding principles” for gatherings as a result:

  • Organizers should stay up to date on current conditions in their area when deciding whether to postpone, cancel, or significantly reduce the number of attendees for gatherings.
  • The more people gather in a crowd and the longer people interact with each other, the greater the risk of COVID-19 spreading.
  • The higher the level of community transmission in the area where the crowd will be, the higher the risk of COVID-19 spreading at the gathering.
  • The size of an event or gathering should be determined based on state, local, territorial, or tribal safety laws and regulations.

Can Contact Tracing Help?

Contact tracing, which is the practice of identifying people who have an infectious disease and those they came in contact with to try to stop the spread of the disease, may help reduce the spread of the virus after people are in crowds, but it has serious limitations, Cennimo says.

“There is too much pre-symptomatic and asymptomatic spread,” he says. “If cases were identified, contact tracing could still get the second order cases, but we would already have significant spread.”

Given the lag in time that it takes for people to show symptoms—if they do at all—and the long wait times to get testing results, people can be spreading the virus to others for days before they’re aware that they’re infected, Cennimo says. “If it takes any length of time to get them in to be tested and they do not quarantine in the meantime, they can still be spreading,” he says.

Overall, experts say it’s really best to avoid crowds if you can. “I would not want to be in a large group, period—certainly not without masks,” Cennimo says.

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Article Sources
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