Prince Edward positivity rate may be elevated
Many Prince Edward County residents have been confused in recent weeks as to why the county is displaying one of the highest percent positivity rates for COVID-19 testing in the state when Prince Edward’s case numbers have been trending downward for more than three weeks.
Local health officials say this number is heavily dependent on testing trends and is not a reliable indicator of viral prevalence in the community.
The Virginia Department of Health (VDH) provides weekly updates of localities’ percent positivity rate among PCR (Polymerase Chain Reaction) COVID-19 tests.
From Jan. 30 to Feb. 12, Prince Edward tested 821 individuals, of which 127 results came back positive. Because of this, the county’s most recent PCR percent positivity rating as of Monday, Feb. 15, was listed as 15.5%.
The number was even higher the week of January 16 to January 29 when the county’s positivity rating reached 16.2%.
While many Virginia counties currently display positivity ratings above 10%, only a handful, including places like Stafford, Amelia and Chesapeake, have a higher rating than Prince Edward.
Piedmont Health District Director Dr. H. Robert Nash said a locality’s percent positivity figures are highly dependent on who is getting tested.
“Many testing sites are now restricting testing to those individuals with symptoms of COVID again, just as was being done when testing availability was scarce,” Nash said Tuesday, Feb. 16. “When the large, drive-thru testing events were being held, we only had a positivity rate of 0.7%, also not a good predictor of viral prevalence in the community.”
Nash said positivity rates in the county were once very low because so many people with no symptoms, history of close contact or exposure to the coronavirus were coming to large testing events “just to be sure.”
He said the county is now seeing the opposite effect where only the most symptomatic and seriously ill are tested, ultimately driving the positivity rates up.
“One always has to be careful of percentages,” he continued. “If only 20 people are tested, and only five test positive in a whole county, then the test positivity rate is 25%, but that does not mean that 25% of the county population is positive … percentages can be very misleading.”