SEATTLE -- Spring brought a wave of cancellations that shut down professional baseball, basketball, concerts, movie theaters, youth sports, school plays, camping in state parks and all sorts of other events to slow the spread of the novel coronavirus.
Then, on May 25, came the brutal death of George Floyd as a Minneapolis police officer held a knee to his neck, an act of violence that set off large protests in a powerful grassroots justice movement that also unfolded as a kind of mass experiment about the risks of such outdoor gatherings amid a global pandemic.
More than one month after Floyd's death, the number of COVID-19 cases is rising in some parts of Washington state, including the Seattle area, and the national tally of new cases last week reached all-time highs.
But some researchers say that the protests do not appear to be significantly driving this surge. This helps bolster the case that the coronavirus generally does not transmit as easily outdoors, where even a gentle breeze can help diffuse the virus, compared to confined indoor spaces.
"I would say that outside makes a big difference because of much more air circulation," said Dr. Jared Baeten, a vice dean at the University of Washington's School of Public Health, who donned a mask and joined in the June 12 March of Silence through Seattle that drew an estimated 60,000 people.
In King County, the epicenter of Washington's protests, health investigators have tracked -- during a 19-day span in June -- less than 5% of 1,008 total positive cases to people who attended protests. In other cities, including Minneapolis and Portland, researchers have yet to find that protests, where many were masked, have caused major spikes in cases.
"The data may be imperfect but ... neither here in King County, or elsewhere in the county, where health care authorities are looking, have we been able to document that or find strong evidence of that," said Dr. Jeffrey Duchin, health officer of Public Health -- Seattle & King County in remarks to reporters on Friday.
Others have reached a similar conclusion.
A working paper -- yet to be peer reviewed -- from the National Bureau of Economic Research analyzed data from protests in 315 large cities and found "no evidence that urban protests reignited COVID-19 case growth during the more than three weeks following the protest." The study also cited evidence that protests prompted more stay-at-home behavior by those who didn't go to the protests.
Still, some public health officials offer a more skeptical view.