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Health Officials Address Accuracy of Positivity Rates, Lab Test Reports

The Florida Department of Health confirmed Wednesday that some private labs were not reporting negative COVID-19 test results to them, as required by the state.

That ended up leading to 100 percent positivity rates being reported for those labs.

Department of Health spokeswoman Olga Connor told Miami television station WPLG in an email that public and private labs are required to report all of their COVID-19 test results to the state, regardless of whether the tests are positive or negative.

“In recent days, the Florida Department of Health noticed that some smaller, private labs weren’t reporting negative test result data to the state,” Connor wrote. “The Department immediately began working with those labs to ensure that all results were being reported in order to provide comprehensive and transparent data.”

She went on to say that the Department of Health will continue to educate labs “on the proper protocol for reporting COVID-19 test results.”

More than 1,100 labs have reported test results to the state through July 13.

Out of those, more than 460 reported 100 percent positivity rates, or near that level:

-Orlando Health reported 512 positive cases and 10 negative cases for a 98 percent infection rate

-LAB24 Inc, with a location in Boca Raton, reported 464 positive test results and zero negative cases for a 100 percent positive infection rate.

-The VA Medical Center in West Palm Beach Lab reported 115 positive test results and zero negative results for a 100 percent positive infection rate.

-Florida Community Health Centers Inc. reported 67 positive cases and zero negative cases for a 100 percent positive rate.

On the other hand, some experts say the state might be minimizing the depth of its coronavirus problem by underreporting its rate of positive tests.

They explain that the method used to calculate the “positivity rate” puts more emphasis on negative tests, thereby skewing the results in that direction.

A person who tests positive is counted only once, although negative tests can be counted repeatedly if the same person gets tested multiple times.

The state also reportedly mixes two different types of tests, including one that produces more false negative results.

The upshot is that the rate of positive tests provided by the state health officials makes the situation appear better than it is, experts say.

“There is a peculiar odor around the data in Florida and there has been for some time,” says Dr. William Hanage, associate professor of epidemiology at Harvard’s T.H. Chan School of Public Health.

Olivier Lacan, a volunteer for the COVID Tracking Project, adds, “The right wing is saying the numbers can’t be trusted; the left is saying the numbers might be higher. Just show the math!”

Gov. Ron DeSantis and his team have cited the positivity rate to justify reopening schools and businesses.

“We only count the positive test once,” Alina Alonso, the head of the Palm Beach County Department of Health, told Palm Beach County commissioners on July 7.

“We do count the negative tests more than once because there are reasons for people testing negative and getting multiple test results. But the positives by name are only captured once,” she said.

That means that the same person with multiple negative tests can be counted several times.

According to Jason Salemi, associate professor of epidemiology at the University of South Florida’s College of Public Health, “If the same people are testing negative and getting reported over and over … well, the results could be quite different from a true person-level analysis.”

On Wednesday evening, Alberto Moscoso, the spokesman for the Florida Department of Health, said the state counts multiple negative tests for the same person since “a negative test only reflects the individual’s status at the moment the specimen was collected. Since a person who tested negative previously remains susceptible to the virus, the subsequent test is still included in the denominator of the positivity rate calculation.”

Experts say the state’s decision earlier this month to include Antigen tests in their count could also drive down the positivity rate, since a significant number of those Antigen tests could be false negatives.