SEATTLE -- Social distancing efforts appear to be making some progress in slowing the spread of COVID-19 in King County, according to two new studies, but those efforts still need to continue to prevent the disease from overwhelming the medical system, the authors said.
Bellevue-based Institute for Disease Modeling first used anonymous mobility data from the Department of Health and Facebook to show that King County residents indeed began travelling less since early March as large employers told workers to work from home and non-essential businesses and the entire local entertainment industry shut down as the virus began to spread. (Full study here)
Researchers then compared that mobility data to the testing and diagnosis data of COVID-19 cases in King County over the past few weeks and the results were encouraging.
They found that a measure of transmission, called the effective reproductive number, dropped by about half from about 2.7 in late February to roughly 1.4 on March 18. (Full study here)
"This number represents the number of new transmissions stemming from each infection," researchers said. "In order to sustain a drop in new cases, each infected person, on average, must infect fewer than one person."
Full IDM Studies: Understanding the Impact of COVID-19 Police Change | Social Distancing Have Reduced COVID-19 Transmissions
But as long as that number remains greater than 1, the area will continue to see an increase in COVID-19 cases and, sadly, more deaths.
"We are seeing a positive effect from the social distancing and other measures we’ve put in place, although significant numbers of cases and deaths continue to occur,” Dr. Jeff Duchin, Seattle-King County Public Health Officer said a press release announcing the studies. “It’s important to note that these findings are based on relatively few cases and persons tested, and therefore come with a great deal of uncertainty. Continued monitoring with the measures in place will lead to more reliable data.”
Duchin also stressed that despite the encouraging findings, we shouldn't take them as an indication to relax the social distancing strategy.
"The threat of a rebound that could overwhelm the healthcare system remains and will remain for the foreseeable future if we let up too soon," Duchin said. “We absolutely need to continue the current distancing measures and to continue monitoring the epidemic and its impacts as testing increases to determine if any adjustment to our response is needed."
King County reports nearly 2,200 cases of COVID-19 now with 141 deaths through Sunday.
Even now, while there is still some hospital capacity in King County, there have been "significant impacts" on hospital operations as the number of cases increase, according to the Northwest Healthcare Response. That includes continued shortages on personal protection gear.
Dr. Daniel Klein, who heads up the computational research team at IDM, points out the epidemic was still growing in King County.
"The main takeaway here is though we’ve made some great headway, our progress is precarious and insufficient," Klein said.
Gov. Inslee's Stay-At-Home order remains in effect for King County and the rest of the state. It was originally a 2-week order, but Inslee strongly hinted over the weekend that the order may have to be extended.