FDA Says Mutated Coronavirus Can Produce False Negative Results

FLORIDA — The U.S. Food and Drug Administration is alerting clinical laboratory staff and health care providers in Florida and other states that genetic variations of the coronavirus may lead to false negative results in certain kinds of coronavirus tests.

In December the FDA confirmed that the coronavirus can mutate over time after a quickly spreading genetic variation of the coronavirus began affecting people in the United Kingdom who has specific genetic traits.

The first case in the United States was discovered in Colorado Dec. 30. The following day, three cases of the new strain appeared in Florida, according to the Florida Department of Health.

On Friday, the Centers for Disease Control and Prevention said more than half of all the cases of the variant from the United Kingdom (22 cases) have been found in Florida. California has 32 cases. Three cases have appeared in Colorado. Two cases have been detected in Connecticut. And there has been one case each in New York, Texas, Pennsylvania and Georgia.

While the variant, known as B.1.1.7, is not expected to be resistant to the coronavirus vaccines, the FDA has identified three molecular coronavirus tests that can give false negative results if the person is infected with the variant.

There are two different types of test for the coronavirus - diagnostic and antibody tests. Molecular tests are a type of diagnostic test, according to the FDA.

"Since molecular tests look for a specific sequence, it is possible for certain virus mutations to affect the performance of certain tests if the mutation is in a region of the genome targeted by the test," said the FDA in a letter to clinical laboratory staff and health care providers issued Friday.

The tests that can produce false negative results include the Accula SARS-Cov-2 Test, the TaqPath COVID-19 Combo Kit and the Linea COVID-19 Assay Kit. The FDA recommends that people who have a false negative result following one of these tests be retested.

"Molecular tests are typically highly sensitive for the detection of the SARS-CoV-2 virus. However, all diagnostic tests may be subject to false negative results, and the risk of false negative results may increase when testing patients with genetic variants of SARS-CoV-2," the FDA said.

The news from the FDA comes as Florida reported its second-highest single-day record for positive coronavirus cases with 19,530 more people infected. There were 19,816 new cases reported on Thursday and 17,783 new cases on Wednesday.

The state has had 1,449,252 positive coronavirus cases (about one in every 15 Floridians) since the pandemic began. The Florida Department of Health said 22,666 Floridians have died.

During a news conference Friday, Florida Gov. Ron DeSantis said he will continue the effort to roll out vaccines to residents age 65 and over, an effort that began this week with sundry snags as registration systems throughout the state were overwhelmed by seniors seeking the vaccine.

"This is the most effective tool we have to battle the pandemic," said DeSantis. "I mean, if we continue to vaccinate senior citizens, you are going to reduce the ceiling for hospitalizations, you absolutely will, because those are the most likely to get hospitalized. You will reduce the mortality rate because the mortality has been concentrated in the 65 and plus."

As of Thursday, the DOH said 419,416 Floridians have received their first dose of the vaccine and 24,200 have received a second dose.

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