Crowded protests spark concerns about fresh outbreaks of the deadly coronavirus - The Washington Post

And because the virus can be spread by people with no symptoms, it can be impossible to figure out whom to avoid.

As of Sunday, the United States had recorded 1.7 million coronavirus infections and 103,000 covid-19 deaths — a disproportionate number of them black and brown people.

“Crowded protests, like any large gathering of people in a close space, can help facilitate the spread of covid-19, which is why it’s so important participants wear masks, eye protection and bring hand-gel,” Saskia Popescu, an infectious-disease epidemiologist at George Mason University’s Schar School of Policy and Government, wrote in an email.

In one study — which has yet to be peer reviewed — of 7,324 infected people in China, only two contracted it outdoors.

Researchers in Japan who looked at a small number of cases concluded that the chances of transmitting the virus are nearly 19 times greater indoors than out.

“There are so many variables at play here: Extent of social distancing, ambient environmental conditions, number of people, extent of mask use, the effect of things like tear gas [and] pepper spray on susceptibility via different transmission routes,” Angela Rasmussen, a virologist at the Center for Infection and Immunity at Columbia University’s Mailman School of Public Health, wrote in an email.

Linsey Marr, a professor of civil and environmental engineering at Virginia Tech, who specializes in airborne transmission of viruses, said that even when people are crowded against each other, it takes time to transmit the virus in significant amounts — especially outdoors.

She said she would worry if the density of the crowd approximated the conditions of packed seats in a basketball arena, and if people did not move much for at least a half-hour.

Mask-wearing by infected people would cut down on the spread of respiratory droplets, offering some protection to people nearby.

Unless they are rated N95 or better, however, masks offer only limited protection against the microscopic virus for the people wearing them.

Frieden raised one other aspect of the protests that may contribute to the spread of the virus: the breakdown of trust in government.

Columbia University student Juliet Shatkin, 26, said her friends were “nervous about coronavirus,” so they did not join her during a protest Saturday on Manhattan’s Upper East Side.

“It’s scary, but I don’t know,” Shatkin said.

Elise Barr, a teacher at a child-care center, wore a mask to attend a protest Sunday in Kansas City, Mo., but she said she was not worried about catching the virus.