RALEIGH, N.C. (WNCN) — COVID-19 tests in North Carolina are coming back positive at a record rate — more than 1 in 4 of the most recent batch.

But a closer look at the individual counties reveals some key differences that tend to hinge on how much routine testing that county is doing.

The fewer of those tests, the worse that county is probably doing.

“When we see quick increases in percent positive and quick decreases in percent positive, that could have to do more with the sheer volume of testing occurring,” said Dr. Pia MacDonald, an epidemiologist at RTI International.

The state Department of Health and Human Services said Monday that 27.4 percent of tests done Saturday were found to be positive, the highest single-day rate of the pandemic.

That rate has been at 20 percent or higher on six of the past seven days after never surpassing 17 percent at any other point.

For each county, NCDHHS releases the total number of tests done over the previous two weeks along with the percent of them that were positive. CBS17.com then determined each county’s per capita testing rate — how many tests each county did for every 10,000 people who live there — during that time to quantify which counties are doing the most tests per resident.

By that measure, the top four counties are all in central North Carolina, with Wake County doing 1,235 tests for every 10,000 residents. Orange County (910) was second, followed by Franklin (877) and Durham (840).

The percent positive in each of those counties was significantly below that statewide average, with Orange at 11.2 percent and Wake at 15.7 percent.

At the other extreme is Gates County, which had the fewest tests per capita (155) along with the state’s highest percent positive during the past two weeks — 27.9 percent.

“In urban counties, there’s more of an ability to ramp up testing quickly than in rural counties where it’s harder to increase the volume of testing,” MacDonald said.

A rule of thumb throughout the pandemic has been that a high percent positive is usually a sign that more testing is needed because only the sick and symptomatic people are being tested.

But it’s also an indication of just how quickly the omicron variant is sweeping through the state and the nation “even beyond what we saw with delta,” said Dr. David Wohl, an infectious disease specialist at the University of North Carolina School of Medicine.

MacDonald says more routine testing would help bring those numbers down, and so would doubling down on efforts to tamp the spread — chiefly by increasing the vaccination and booster numbers.

“With improved vaccination rates, the virus has a harder time spreading quickly,” she said.

But Wohl wonders if it’s too late for so much emphasis on testing.

“I think we’re going to get more used to a posture where, before, we isolated people, we identified them, we isolated them, we quarantine their contacts,” Wohl said. “With omicron spreading as widely as it is and involving so many people, that’s just not feasible anymore. And it may not be given, again, most of us are not going to end up really sick because we’re vaccinated, boosted.”

CBS 17’s Joedy McCreary has been tracking COVID-19 figures since March 2020, compiling data from federal, state, and local sources to deliver a clear snapshot of what the coronavirus situation looks like now and what it could look like in the future.