U.S. will finally use coronavirus testing method that let Wuhan test 6.5 million people in 10 days
The U.S. Food and Drug Administration on Saturday gave emergency use authorization to a coronavirus testing method that could massively ramp up testing capabilities for the country.
The FDA is allowing Quest Diagnostics to test individual samples for coronavirus using a method known as batch testing, which mixes specimens from multiple people and tests the combined sample for coronavirus instead of testing samples one by one.
The Quest Diagnostics test will be the first in the U.S. with approval for use in batch testing. The FDA is allowing Quest to pool samples of up to four people.
Batch testing played a key role in two of the most impressive mass testing efforts to date—in Wuhan, China, in May, when the city government tested almost 10 million people, and in Beijing in June, when authorities tested thousands of workers in factories that reported one confirmed case. The technique could be a game-changer for the U.S., representing a big step toward safely reopening the economy.
Public health officials in Wuhan—the site of the very first coronavirus outbreak—used batch testing in May during the city government’s campaign to test the entire population for the coronavirus. The city tested 9.9 million people, the majority within 10 days, to help contain a small second outbreak. It used batch testing to speed up the process.
Officials in Wuhan tested up to five combined samples at once. If the test came back positive, all five people were tested individually, but if it came back negative, then all five could be declared free of coronavirus without needing individual tests, which consume more time and resources. Patients with negative results also receive the result faster than they would with individual tests.
Batch testing is most useful when trying to test a large number of people who likely have a low infection rate. If infection is widespread, then batch tests will turn up positive results frequently and won’t end up cutting down on processing time. Wuhan’s mass testing of 9.9 million people yielded 300 positive test results, all of which were asymptomatic cases, according to government data.
Public health officials in Germany, Israel, and Thailand have also carried out batch testing for coronavirus. Beijing deployed the method in June during an upswing in new cases that health authorities managed to curb. City officials tested every one of the city’s more than 100,000 delivery workers, who were seen as a bellwether for Beijing’s infection rate.
“This [emergency use authorization] for sample pooling is an important step forward in getting more COVID-19 tests for more Americans more quickly while preserving testing supplies,” FDA commissioner Stephen M. Hahn said in a statement. “Sample pooling becomes especially important as infection rates decline and we begin testing larger portions of the population.”
There were some concerns during Wuhan’s batch testing that the samples might be diluted and lead to false-negative results. The FDA said in its statement on the emergency use authorization that Quest ran tests to check whether dilution could be a problem, and the tests correctly identified all the positive samples.
The batch method also saves testing kits. The technique uses one kit for four samples, instead of four separate kits; this could aid U.S. cities still suffering from shortages months into the pandemic.
Batch testing could help the U.S. ramp up its daily testing numbers to the level recommended by researchers for a “safe social reopening.” In an April 20 report, Harvard University researchers estimated the U.S. should reach 5 million tests per day by early June and 20 million tests per day “ideally by late July” to return safely to pre-pandemic economic and social activity. According to the COVID Tracking Project, the highest number of tests the U.S. has processed in one day was 851,788 tests on July 17.
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