COVID-19 caseload keeps climbing. Testing explains only part of the trend.

Coronavirus testing efforts in Charlotte have increased dramatically since the start of the pandemic, when North Carolina counties were receiving just three test kits at a time.

More testing will inevitably lead to more cases being detected, health officials say. As labs process additional tests, health departments across North Carolina have reported higher numbers of COVID-19 diagnoses.

In April and May, according to a Charlotte Observer analysis of publicly-available health data, the rise in cases largely kept pace with the increase in testing in Mecklenburg County.

But a review of testing and case data from June shows that the latest increase in known infections cannot be explained by increased testing alone.

“There’s definitely more at play,” Dr. Katie Passaretti, Atrium Health’s medical director of infection prevention, told The Charlotte Observer.

“We’ve clearly seen over the past weeks, really since Memorial Day, a steady creep in the hospitalizations across the state.”

Community exposure risks to COVID-19 have moderately increased as Charlotte moved away from strict stay-at-home orders, Passaretti said. Health officials say the wider community spread means they are unable to pinpoint exactly how someone became infected, such as traveling to a coronavirus hotspot or coming into close contact with someone who has COVID-19.

From April to May, for example, the average number of daily tests administered locally increased from 660 to 1,558 — or by a factor of 2.4. The corresponding average of new cases reported per day increased from 40 to 85 — a factor of 2.1.

In June, testing increased again but not by as much. And the pace of new cases exceeded the pace of more testing and the pace of infection from previous months, data show.

On average, 2,803 coronavirus tests were given daily in Mecklenburg in June. That’s about 1.8 times more tests compared to May and four times as much testing than in April, according to a Charlotte Observer analysis of county health data.

The corresponding average of new cases increased from 85 in May to 230 in June — a factor of 2.7, an analysis of state-reported health data show.

The data, along with a documented higher percent of positive tests and increased average hospitalizations per week, underscores how more people in and around Charlotte were infected as the region gradually eased restrictions and COVID-19 testing capacity grew.

“If we were widely testing, you would expect to see that percentage going down. But that’s not the case (here) — the percentage is going higher,” said Michael Thompson, an associate professor and associate chair of UNC Charlotte’s public health sciences department.

“It means the prevalence of the disease in the community is increasing.”

‘Uncontrolled epidemic’

North Carolina’s seven-day average of positive tests is hovering around 9%, which Gov. Roy Cooper last week called a “stubbornly high percentage of positives.”

Dr. Mandy Cohen, secretary of the state Department of Health and Human Services, has said she wants the positivity rate of tests to be closer to 5%.

Local officials say Mecklenburg’s weekly positivity rate of coronavirus tests, 11.2%, reported through June 30, reflects a “fairly stable” trend. The average percent of positive tests in the month of June — 10.57% — was higher than the average percent in May, 7.39%.

“Looking at that absolute (11%) number, you want that number to fall because you’re testing enough and not finding a ton” of new cases, said UNC Chapel Hill infectious disease modeling expert Kimberly Powers.

“What’s actually behind the increase in cases is we have an uncontrolled epidemic going on ...” Powers said. “There’s more infection around than there was when we first zipped up and shut things down. The threat certainly remains.”

Mecklenburg Public Health Director Gibbie Harris has acknowledged reopening led to some of the ballooning case growth. The number of people needing hospital-level care has increased, too. Still, officials say local hospitals have the capacity needed to treat coronavirus and non-coronavirus patients for now.

The county’s worst day for hospitalizations, so far, came June 29, when 152 people were hospitalized with COVID-19, Mecklenburg data show. For the month of June, the daily average was about 120. In May, the number never reached triple digits. In April, the average was 86.

Health officials are closely monitoring the potential strain on hospitals across the state.

Passaretti said Atrium’s capacity to treat COVID-19 patients is not in the “red zone” yet.

“Hospitals are trying to balance routine care of patients and the volumes we always run with. It gives you not a ton of wiggle room,” she said. “We’re in the yellow zone. We’re quite full — we’re not excessively full.”

Testing plateau

In May, state health officials ramped up daily coronavirus testing targets for individual counties. They also loosened testing criteria for people with less possible exposure risks and symptoms. That move meant a larger population would be tested for COVID-19, potentially detecting further spread of the virus, including among asymptomatic individuals.

Mecklenburg, for instance, followed a tiered testing strategy between early May and June, broadening eligibility criteria to include younger adults and those who “support critical infrastructure.”

The county in early June was instructed to test 20,000 residents daily to help quell future coronavirus outbreaks. That figure was quickly slashed to as low as 4,000 due to testing capacity and supplies among local healthcare providers.

While more testing has contributed to more lab-confirmed coronavirus cases, county health data show the number of tests given daily since mid-June has plateaued.

Still, Mecklenburg officials have more data available about the local COVID-19 outbreak, now that CVS Health reports its daily tests to the county — in addition to Atrium Health and Novant Health, which have been providing testing data since March.

According to the most recent data available, through June 30, more than 150,000 tests have been administered in Mecklenburg.

Tryon Medical Partners, which is not reflected in the county’s data, has done about 9,500 tests at its locations in uptown and Pineville from March through June 26, spokesman Tom Williams told the Observer. The group’s positivity rate was 9%, with the “vast majority” of patients from Mecklenburg, he said.

‘A head of steam’

With increased testing only a partial explanation for the rise new cases, the data may hint at a looming threat for the greater Charlotte area, said Dr. David Rubin, the director of PolicyLab at Children’s Hospital of Philadelphia.

Rubin, a lead investigator for a COVID-19 model that incorporates county-specific trends, said Mecklenburg’s outbreak curve reflects what Arizona and Dallas, Texas, looked like several weeks ago — before emerging as some of the county’s top coronavirus hotspots.

The White House Coronavirus Task Force in May named greater Charlotte as a “location to watch” after sharp increases in week-to-week confirmed cases.

“The more disease burden you build up, it’s a head of steam. When you get to a certain threshold, you lose control of the epidemic because it’s doubling so quickly,” Rubin told the Observer. “Whatever you see is also just a smidge of what you might see in the fall.”

Similar concerns are shared in other parts of the Charlotte region.

In neighboring Gaston County, officials said the percentage of positive tests has more than tripled since mid-May, surpassing 17% last week. Meanwhile, testing capacity has more than doubled, which county spokesman Adam Gaub said is “partly due to a change in CDC guidance on who should be tested, but also due to a wider availability of testing material.”

“This is more than just more testing being done,” Gaston Public Health Director Steve Eaton said in a statement last Wednesday, urging residents to take health guidelines and face covering requirements seriously to slow the spread of the virus.

In Rock Hill, S.C., elected leaders this week approved an emergency mask mandate, after York County broke its record of daily new cases over the weekend and state health officials reported a record-high number of COVID-19 deaths in a 24-hour period.

Even with improved detection, public health officials and virus experts say the true total of COVID-19 cases is likely far more than what lab testing has captured.

And, increased access to testing sites could be crucial to understanding demographic shifts in the pandemic, Thompson, of UNCC said.

“We need better coverage — we don’t know what we don’t know,” Thompson said. “The science right now is really messy. People’s interpretations of what we do know keeps changing.”

Rubin said local officials could “lose control” of the pandemic if they hesitate to impose new health guidelines, or fail to enforce measures like wearing face masks out in public.

“It’s not a light switch, and you might well be beyond a point where you can manage that acceleration,” Rubin said.

“If we don’t create the right level of community response to break the transmission chain, you could be weeks away from going into a more epidemic pattern.”