Human behavior, Superspreader 'explosions' continue to hinder pandemic control efforts

Superspreader 'explosions' continue to plague pandemic efforts New coronavirus strains are a risk, but experts say human behavior and social interactions that lead to superspreader events remain the most serious threat. NBC News

Superspreader events that first seeded the coronavirus in the United States are keeping the pandemic smoldering, with experts pointing to human behavior and social circles as the main drivers.

The problem persists even as the country nears the milestone of having half of its population fully vaccinated. At a church camp in South Texas in late June, an outbreak was linked to more than 125 cases of Covid-19. Eighty-five infections in central Illinois were traced back to a summer camp in mid-June.

Similar examples have emerged internationally: A disco party held on June 26 in the Netherlands was later tied to 160 new cases, and the Miss Mexico pageant in the city of Chihuahua was cut short in early July after nearly half of the contestants tested positive.

Throughout the pandemic, superspreaders — infected individuals who disproportionately spread the virus to many others — have fueled clusters of infection that often make the virus difficult to contain. In other words, when the coronavirus infiltrates communities, superspreader events are the seminal moments when the pathogen lays siege.

Now, with the more-contagious delta variant of the virus circulating in the United States and around the world, experts warn that without adequate mitigation measures, superspreader events are a major threat to vulnerable communities and risk jeopardizing hard-fought gains to drive down the number of cases.

But even as the pandemic evolves and new variants emerge that are more transmissible or can cause more severe disease, human behavior remains one of the biggest pieces of the equation.

"It's not just about the variants. It’s also about how people are interacting," said David Dowdy, an associate professor of infectious disease epidemiology at the Johns Hopkins Bloomberg School of Public Health. "Right now, people are definitely distancing less, masking less, going to larger gatherings, and meanwhile, vaccination rates are not going up all that fast."

All of these things combined can create a perfect storm, increasing the odds that new transmissions spiral out of control. ...

One way to prevent big spikes in infections from the delta variant is to minimize the likelihood that superspreader events will occur, said Joshua Batson, chief data scientist at The Public Health Company, a California-based startup that uses technology to monitor and contain infectious disease outbreaks. This involves doubling down on vaccination efforts and may require reimposing certain restrictions, such as rules for social distancing and wearing masks, in areas where outbreaks are happening.

"Mathematically, if you remove the superspreading events, we don't have a pandemic," Batson said. "If you just concentrate on these scenarios where the really bad things happen, you'll have a disease that will kind of just sputter out." ...