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FDA approves testing pooled samples to speed up coronavirus detection

2020-07-22

The U.S. Federal Drug Administration (FDA) approved testing pooled samples to help speed up the coronavirus detection process and conserve supplies.

The way it works is that the samples from several people are tested using one kit. If all are negative, then no one has it. If any coronavirus shows up in the mix, then all must be tested to determine which of them is infected.

The FDA reissued an existing emergency use authorization to Quest Diagnostics, renewing a permission initially granted in March. The first COVID-19 diagnostic test to be authorized for pooled samples, it can allow for testing on up to four individual swab specimens at a time, the FDA said.

The goal is to allow for more people to be tested quickly, using fewer testing resources, the FDA said, noting that the lower the prevalence in a given area, the more efficient this strategy is.

The measure was taken as cases skyrocket across parts of the U.S. that resumed activity before the first wave of infection had completely passed.

It doesn’t work as well in hotspots such as nursing homes and meat-packing plants where outbreaks are common, because the probability of a positive group test is higher, making individual testing all but inevitable.

“This EUA for sample pooling is an important step forward in getting more COVID-19 tests to more Americans more quickly while preserving testing supplies,” FDA Commissioner Dr. Stephen Hahn said in a statement. “Sample pooling becomes especially important as infection rates decline and we begin testing larger portions of the population.”

Potential pitfalls include the possibility of a false negative, if one person is infected but the sample is too diluted by the healthy ones in the group to show up, as NPR reported.

But the benefits of ramping up testing are undeniable, especially given the potential for asymptomatic or pre-symptomatic spread, health officials say.

“Pooling would give us the capacity to go from half a million tests per day to potentially 5 million individuals tested per day,” White House coronavirus task force member Dr. Deborah Birx, said last month, according to CNN.

The concept itself isn’t new, the Associated Press pointed out. It dates back to World War 2, when it was used to screen U.S. draftees for syphilis. More recently, AP said, China used the strategy to test Wuhan’s 11 million residents for coronavirus in the city where it first broke out.

“Widescale pooled testing can be highly cost effective and time saving to potentially quickly identify positive cases, quarantine them, and contract trace from there forward to prevent further spread of disease in a community,” Dr. Manisha Juthani, associate professor of medicine and epidemiology and an infectious disease specialist at Yale School of Medicine, told CNN.