Limits on social interaction seem to be slowing the spread of the novel coronavirus in King County, health officials said Monday.
Two studies from the Bellevue-based Institute for Disease Modeling appear to show people have been moving around less and that each person carrying the virus is now infecting fewer people on average than they were a month ago.
"What we're doing now appears to be working," Dr. Jeff Duchin, King County's top public health official, said at a news conference.
But, he warned, if so-called "social distancing" measures are loosened too soon, "the outbreak will come roaring back."
"We should in no way take these findings as an indication to relax our social distancing strategy," Duchin said, adding that social restrictions will likely remain in place for weeks or months.
Actions meant to reduce person-to-person interaction have been mounting for weeks in Washington state, from limits on mass gatherings to school closures to, finally, a statewide stay-at-home order. King County, which saw the country's first coronavirus-related death a month ago and first large-scale outbreak, has had some of the earliest restrictions.
"Daily life has been turned upside down, and I know people are anxious, seeing days pass without a paycheck, not knowing when kids will get back to school," King County Executive Dow Constantine said in a news release Monday.
The study results, he added, "should strengthen our resolve to do everything we can to keep people safe, and to get through this crisis together."
One study used Facebook mobility data to see how people's movements have changed over the past month. It concluded movement in the Seattle area "reduced dramatically" since early March.
However, movement jumped over each of the past three weekends, highlighting potential challenges in getting people to adhere to widespread social distancing in the long term, researchers said. They also cautioned that, even if mobility ground to a complete halt, the virus would continue to spread within households and other close personal circles.
Another study sought to model how quickly the virus was spreading. The model estimated that, on March 1, each person carrying the virus spread it to an average of 2.7 people.
By March 18, each infected person was infecting an average of 1.4 people. The virus likely was still spreading, but more slowly because people were interacting less and taking precautions.
"Our main result is that the epidemic has slowed, but that more progress is necessary," researchers wrote.
Seattle Mayor Jenny Durkan urged residents to continue practicing social distancing, calling it "the only tool that we have towards slowing the virus."
"With no cure or vaccine, it’s what we can do to save lives and to mitigate against overwhelming our regional health care system," Durkan said in a news release. "We also know we have to continue these measures for the foreseeable future."