When Gov. Jay Inslee on Monday shut down many businesses, banned gatherings and ordered Washingtonians to stay at home, he said the restrictions will remain in place for at least two weeks.
But public health experts say there's nothing particularly significant about a two-week interval -- and that it will likely take longer to slow the spread of the new coronavirus in a meaningful way.
"I don't know of a magic formula for why we're talking about two weeks," said Peter Rabinowitz, co-director of the University of Washington MetaCenter for Pandemic Disease Preparedness. The period does correspond roughly to the virus's estimated incubation period, which means it will take at least that long to determine how well the new measures are working, he said.
"It's a reasonable period for reassessing the impact," Rabinowitz said. "But I'm not personally expecting that in two weeks we will be out of the woods."
The number of confirmed infections in the state continues to rise steadily and appears to still be doubling every six days or so, jumping from about 1,000 on March 17 to 2,469 on Tuesday.
"If you look at the mountain of cases that are coming in Washington, we're still going up, we're not at the top yet," Rabinowitz said. "Until we are clearly showing a decline in new cases, it doesn't seem like we should be talking about relaxing measures."
But if Washington residents adhere to the new restrictions for two weeks, it could significantly reduce the number of new infections and give health systems some much-needed breathing room, said Daniel Klein, head of the computational research team at the Institute for Disease Modeling in Bellevue, which has been helping Inslee and public health officials track and project the epidemic's course.
"Imagine it's like a conveyor belt," Klein said. Patients showing up at hospitals today were infected several days ago, and hospitals are already beginning to run out of equipment. "What this two-week period really does is let us put a pause on the conveyor belt to slow things down and give the system a chance to catch up."
Klein and his colleagues have estimated it will take about a 75% reduction in social contact and disease transmission to bring the epidemic under control. Now they are analyzing things like vehicle traffic patterns to figure out the impact of measures already in place -- and the added benefits from the latest restrictions. They expect to have some preliminary results this week.
"As we see reductions in people moving around and so forth, these are good things and they will bring down transmission," Klein said. By the end of the two-week period, the modelers hope to have a clearer picture of the magnitude of the effect and whether it's approaching that 75% target.
In China, it took two months of essentially locking down vast urban areas to bring the disease under control, said Chunhuei Chi, director of the Center for Global Health at Oregon State University. In the United States, the local and national response has been much slower and less extreme.
As a result, the U.S. seems to be closely tracking what happened in Italy, where the epidemic exploded from a few cases in February to nearly 64,000 diagnosed cases this week. Doctors are being forced to ration care and supplies, including lifesaving ventilators, and medical students who have just graduated are being pressed into service before they are licensed.
"The U.S. is only about seven to 10 days behind Italy," Chi said.
The "stay home" orders issued Monday by Inslee and Oregon Gov. Kate Brown will make a difference locally, Chi said -- but they need to be combined with widespread testing to identify infected people, followed by quarantine to keep them from infecting others -- a strategy that worked well in Taiwan.
Testing capacity is increasing in Washington, with UW Medicine labs now processing about 3,000 samples a day and expecting to ramp up to 5,000 this week, said Judith Wasserheit, chair of the UW Department of Global Health. Public Health -- Seattle & King County this week launched a surveillance program called SCAN, collecting and analyzing about 300 specimens a day from volunteers who use self-testing kits to swab their own noses then ship the samples back to the lab.
But overwhelmed health officials in King and Snohomish counties have been forced to scale back contact tracing -- the shoe-leather epidemiology of identifying everyone who might have come into contact with an infected person and requesting self-quarantine. The agencies are now only reaching out to people known to have been exposed to a confirmed case.
At the national level, President Donald Trump also invoked an approximately two-week period when on March 16 he announced a 15-day plan to slow the spread of the virus, asking people to work from home and avoid large gatherings. Now, he's raising the possibility of backing off some of those measures to ease the economic impact -- something Chi says would be "irresponsible," and lead to a surge in infections and deaths.
Washington state also needs to take care not to lift restrictions too early, Wasserheit said. "We don't know whether it's two weeks or two months that will be needed to flatten that curve," she said. "If they remove that order, I think it's likely we would see a rebound in the spread of infection."
The Institute for Disease Modeling's work confirms the risk, Klein said.
"If we just go back to business as usual and we open all the schools, and everybody goes back to work in two weeks ... our models show that there is the potential for it to come right back."
