Hopkins officials calculate state positivity rates using data provided by The COVID Tracking Project. On Friday, the project changed how it maps Maryland’s case data, causing Hopkins' positivity rate for the state appear to plummet from earlier in the week, when it was above 5%.
Previously, Hopkins calculated the positivity rate using the number of people tested. That meant that individuals who are tested multiple times, regardless of their results, were counted only once in the university’s calculation.
The project counts “total tests”to now include all viral tests performed, Dr. Jennifer Nuzzo, lead epidemiologist for Hopkins' coronavirus resource center’s Testing Insights Initiative, said Saturday in a statement.
“With this significant change, we will once again review our data inputs and calculations to insure that our numbers reflect the most responsible public health calculation of test positivity,” Nuzzo said.
The World Health Organization says governments should wait until their jurisdictions' positivity rates are below 5% for 14 consecutive days before beginning to ease virus-related restrictions. Maryland has been under this threshold since July, according to the state’s reported figures.
Maryland officials reported that Prince George’s County, at 5.38%, was the only state jurisdiction with a positivity rate higher than 5% as of Friday. Somerset County had a rate of 5.04% Thursday, but dropped to 4.1% Friday.