NEW YORK (NYTIMES) - None of the plans for how the United States might safely emerge from the coronavirus lockdown involved thousands of Americans standing shoulder to shoulder in the streets of major cities or coughing uncontrollably when authorities used tear gas to disperse them. No one planned on protesters being herded into crowded prison buses or left in crowded cells.

Before the eruption of outrage over the killing of Mr George Floyd in police custody in Minneapolis, debates about reopening centred on whether states had adequate systems in place to detect and treat cases of the coronavirus, which has killed more than 110,000 people in the US since the beginning of the year.

But as the protests against police brutality enter a third week, public officials are warily watching for signs that an unanticipated end to social distancing on a mass scale has led to new cases of the virus.

The question has become part of the politicised debate over the economic repercussions of the lockdown, which some critics have argued went too far.

And on Sunday (June 7), infectious disease experts on Twitter debated how to supply a reliable estimate of the impact of the protests on virus transmission - or whether trying to do so may wrongly be seen as discouraging participation in the growing racial justice movement.

In what he called a back-of-the-envelope estimate, Dr Trevor Bedford, an expert on the virus at the Fred Hutchinson Cancer Research Institute, wrote on Twitter that each day of protests would result in about 3,000 new cases and 50 to 500 deaths.

Given the racial disparities so far in the pandemic, he noted, those deaths and cases will be disproportionately among black people.

"Societal benefit of continued protests must be weighed against substantial potential impacts to health," he wrote.

Dr Marc Lipsitch, an epidemiologist at Harvard, agreed that Dr Bedford's projections were in the ballpark, and said in an email that he had done "a service'' by making an approximate estimate with explicit assumptions.

MITIGATING IMPACT OF PROTESTS

But he also noted that if states where the virus was still spreading managed to rein it in, that would "massively overshadow the effects of the protests".

If all states had a better ability to detect new cases with tests and contact tracing, or reduce transmission by social distancing and mask-wearing, it would also directly mitigate the impact of the infections acquired at protests by shortening the transmission chain.

About 20,000 new cases are being identified across the country on most days, and about 1,000 new deaths are being announced.

Dr Bedford wrote that his estimates contained a lot of uncertainty. There is no official estimate for how many people are protesting on an average day, for instance. Still, he thought it was important, he said, to provide a framework grounded in epidemiologic principles to counter the offhand assumptions being made by political pundits.

But, in response, other scientists voiced concern that Bedford's posts would "give fodder to those opposing civil rights".

Many epidemiologists, including Dr Bedford, have noted in recent days that America's entrenched racial inequalities themselves translate into disproportionate early deaths and illness among African Americans.

That has been especially evident in the coronavirus pandemic, in which black Americans are dying at about twice the rate of white Americans. A group of more than 1,000 people working in health and medicine signed a letter recently that said protests were, in fact, vital to public health.

"Racism and police violence are major threats to public health in this country, and protest is one of the only options available to people who have been systematically disenfranchised," said Dr Eleanor Murray, an epidemiologist at Boston University.

Because it can take up to two weeks for a newly infected person to show symptoms, health experts expect that any uptick in cases will begin to surface this week.

Demonstrators in several places have contracted the virus, including in Lawrence, Kansas, where someone who attended a protest last weekend tested positive on Friday. That person did not wear a mask while protesting, local officials said. In Athens, Georgia, a county commissioner who attended a protest said that she had tested positive.

In Oklahoma, a college football player who participated in a demonstration revealed that he later tested positive for the virus.

"After attending a protest in Tulsa AND being well protective of myself, I have tested positive for Covid-19," Mr Amen Ogbongbemiga, a linebacker at Oklahoma State University, wrote on Twitter. "Please, if you are going to protest, take care of yourself and stay safe."

Politicians and public health officials have urged demonstrators to wear face coverings and to maintain social distancing. In some places, including Atlanta, Illinois, Los Angeles and Minnesota, officials have also urged protesters to seek coronavirus tests to make sure they have not become infected.

REBELLING AGAINST CORONAVIRUS MEASURES

As the virus has spread across the country, many conservatives have rebelled against the stringent measures supported by public health experts, and there have been skirmishes over wearing masks in public, allowing in-person religious services and placing a premium on restoring the economy over other concerns.

If the virus surges again, said Mr Christopher F. Rufo, director of the Centre on Wealth and Poverty at the Discovery Institute, a conservative think tank, the experts' standing will have been undermined.

"You're going to have half the country that has lost faith almost completely in the public health establishment," he said.

But it may be hard to trace infections to other protesters, who are often marching side by side with strangers. And infectious disease experts have said that any uptick in cases may well be the result of the continued reopening of restaurants, workplaces and mass transit.

In Las Vegas, casinos are reopening. In New York City, long the centre of the coronavirus outbreak in the US, as many as 400,000 workers on Monday can begin returning to construction jobs, manufacturing sites and retail stores as the city enters the first phase of its reopening.

"You cannot pin this on the protests," said Dr Jeffrey Shaman, an epidemiologist at Columbia University, whose projections of the virus' path suggest that US coronavirus deaths will increase in the coming weeks.

"The protests are not in and of themselves going to drive the resurgence in cases. This is associated with all the new opportunities that are providing a way for people to get together and pass the virus to one another."

For their part, activists said the drive to protest in the face of the virus reflected the larger gravity of the moment and the intensity of their passion.

"If I get infected fighting for justice, my soul can sit with that," said Ms Sara Semi, 27, a protester in Minneapolis who wears a mask with a filter and carries cans of disinfectant spray. "I can't sit at home protected by my privileges if others aren't. I can't sit inside my house safe while my friends and neighbours are not. Yes, corona is happening. It's real, it's deadly. But racism kills way more lives."