Expert: Positivity rate doesn’t give full picture of region’s overall health

Though COVID-19 positivity rates continue to move in the right direction in the region, a public health expert said the numbers aren’t all they seem to be.

Maryland announced its daily percentage of positive tests has dropped to record lows the past few days — down to 3.23%.

However, Dr. Joshua Sharfstein, vice dean for public health practice and community engagement at Johns Hopkins’ Bloomberg School of Public Health, said that single number is not showing the whole picture.

“Maryland has a relatively low percent positive, but is identifying a lot of cases, about 1,000 a day,” Sharfstein said. “That’s a large number for the state of Maryland — it’s more than Virginia is identifying, and Virginia is a bigger state.”


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Looking for more information? D.C., Maryland and Virginia are each releasing more data every day. Visit their official sites here: Virginia | Maryland | D.C.


Some areas of Maryland, such as Baltimore, are seeing a surge in cases. Sharfstein also noted the number of patients hospitalized with COVID-19 in Maryland has recently gone up.

“I think the situation in Maryland is: We’re down from a very high peak, but we’re still seeing a fair amount of transmission, and we’re not at all in the clear,” he said.

As for Northern Virginia, there is a somewhat higher percent positive rate, at 6%, but a lower number of cases being identified. But, he points out there has also been an increase in the number of people hospitalized with COVID-19 in Virginia.

Sharfstein said the picture in D.C. is better.

“The number of cases per population is lower, the hospitalizations have come down and are trending down, and the percent positive is low,” he said. “All of the metrics are looking a little better than they were looking before.”

The District has had a percent positive rate of around 3% for over a month, seemingly hitting a plateau. Sharfstein believes that has to do with its neighbors.

“The challenge that D.C. has is it’s located in a region and there’s a lot of virus in the region,” Sharfstein said. “You really won’t expect D.C. to be remarkably low while you’re seeing these higher rates in Virginia and Maryland.”

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