New novel coronavirus cases in Maryland and Virginia have been on a slight decline over the last month, but experts say the region should stay vigilant, in part because of another number: the positivity rate.
D.C.’s seven-day average positivity rate among residents is 3.3%. In Maryland, the rate is 3.63%. Virginia’s is 7.2%.
Rates under 5% are taken to mean enough testing is being done, but rates that hold steady or increase can indicate continued community transmission.
“D.C. is meeting the standard for having enough testing,” said Joshua Sharfstein, vice dean for public health practice and community engagement at the Johns Hopkins Bloomberg School of Public Health. “I think D.C. is still seeing community transmission, and it’s very important for all the precautions to be followed.”
Sharfstein preached caution for Maryland as well.
He said Virginia’s numbers “would give you a sense that perhaps Virginia could use some more testing … and also still has a fair amount of community transmission.”
“It tells us pretty clearly that we’re really not out of the woods yet, and we do have to figure out, why are we still seeing high positivity rates, especially in Virginia?” said Amira Roess, professor of global health and epidemiology at George Mason University, pointing to notably high positivity rates in Prince William County and the Hampton Roads area.
“The positivity rate hasn’t decreased to that 1% that a lot of jurisdictions were hoping for,” she said.
Sharfstein added that the positivity rate should be monitored along with new cases and hospitalizations.
“Right now, we have continued transmission, we still have people in hospitals, we still have a percent positive that indicates that there’s community transmission — and so, across the DMV, a lot of vigilance is still called for,” Sharfstein said.
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