Behind the Florida spike: What testing tells us about recent coronavirus cases

A Virginia testing lab is one reason behind Sunday’s 15,300 positive cases
Dr. Eric Pantaleon, right, checks a box of COVID-19 test kits along with Charnetta Williams, left, of Genetworx, and Heber Mendez, center, at the Genetworx clinical lab Wednesday March 25 , 2020, in Glen Allen, Va.
Dr. Eric Pantaleon, right, checks a box of COVID-19 test kits along with Charnetta Williams, left, of Genetworx, and Heber Mendez, center, at the Genetworx clinical lab Wednesday March 25 , 2020, in Glen Allen, Va. [ STEVE HELBER | AP ]
Published July 14, 2020|Updated July 14, 2020

Florida captured the world’s attention on Sunday after reporting 15,300 coronavirus cases, shattering the record any state had reported on a single day since the pandemic began. However, data analyzed by the Tampa Bay Times shows that half the new cases are linked to tests performed by a single company.

More than 7,000 of the 15,300 positive cases reported on Sunday came from GENETWORx, a testing lab based in Richmond, Va.

The spike in cases came on the same day that almost 100,000 total test results were reported, which is almost 50 percent more than any day so far. GENETWORx accounted for 52,000 of the new results reported by the Florida Department of Health, over half of the total results reported on Sunday.

The share of positive test results processed by GENETWORx was no higher than other labs that analyzed coronavirus tests on that day, but the sheer number of new results reported all at once may have pushed the state to record-setting highs.

GENETWORx is the fourth largest processor of tests for the state, but Sunday’s release of 52,000 new results was unprecedented for the company.

The flood of results may reflect a backlog of reporting by the Florida Department of Health.

“Genetworx is currently processing between 10-13k tests per day in Florida,” GENETWORx CEO William Miller told the Times in an email. “I’m not sure why Florida reported 50k test in one day from us, more than likely it’s a file with a few days’ worth of data.”

The Florida Department of Health could not be reached by phone or email for comment on Monday evening.

GENETWORx has been tied to complaints about delayed test results, the Times reported last month.

The wave of new cases on Sunday was centralized in South Florida.

Miami-Dade alone had over 3,500 infections, which accounts for nearly one quarter of all infections reported on Sunday. And four other counties, including Broward, Orange, Lee and Palm Beach counties, reported over 1,000 new infections, more than each had previously seen in a single day.

The wave of new test results from GENETWORx may also explain this pattern. GENETWORx processes tests performed at locations in Fort Lauderdale, Miami, Palm Beach, and Fort Myers — the same regions that saw the sharpest increase in cases.

Counties in the Tampa Bay area had more moderate increases. Hillsborough saw nearly 800 new cases, while Pinellas and Pasco saw 249 and 127 new cases, respectively.

Although the record-setting tally on Sunday may be partially due to how test results are reported, that is no reason to discount the sheer number of infections, one expert told the Times.

In order to adjust for the number of tests, experts look at the percent of tests that come back positive.

On Sunday about 16 percent of tests returned positive. And that number is relatively low compared to what the state has seen in recent weeks, when the percent of positive test results has reached nearly 20 percent on average.

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Although the percent positive rate is lower than normal, “16 percent is still very troubling,” said José Szapocznik, a professor of public health at the University of Miami. “To me it shows that the prevalence of infections in the population is still going up.”

A percent positive rate above 5 percent indicates insufficient testing, according to guidance from the World Health Organization. A recent study from the Harvard Global Health Institute also indicates that testing in Florida remains far below the optimal target, the New York Times reported on Sunday.

The problem, said Szapocznik, is that “we’re not contact tracing and we’re not rigorously isolating people.” And when infections keep creeping up “there is reason to be extremely concerned.”

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