The FDA authorized its first COVID-19 diagnostic test for pools of samples to let laboratories conserve resources by evaluating several people at once.
Say, for example, you have four individuals who need to be screened for the novel coronavirus—such as a family or a group of employees.
After collecting nasal swabs from each person, a portion of the samples could be combined and tested within a single batch—a single negative result would put them all in the clear, but a positive reading would lead to each sample being tested separately.
“Sample pooling becomes especially important as infection rates decline and we begin testing larger portions of the population,” said FDA Commissioner Stephen Hahn, M.D., in an agency statement. However, infection rates are currently climbing in many states and localities across the U.S.—raising the national average per capita, with new daily confirmed cases topping 77,000 this past week.
At the same time, widespread demand for coronavirus testing and strains on diagnostic supplies—from chemical reagents to swabs to sterile containers—have led to backlogs and long turnaround times for results.
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Batch testing aims to run fewer tests overall while processing more people, faster. But the strategy is designed for areas with a low prevalence of the disease, where most results are expected to be negative, according to the agency.
Quest Diagnostics received the FDA’s green light for pooled testing using the same COVID-19 molecular diagnostic first authorized by the agency in mid-March.
“While there is a concern that combining samples may make it more difficult to detect positives, since pooling in the laboratory dilutes any viral material present in the samples, Quest’s validation data demonstrates that its test correctly identified all of the pooled samples that contained a positive sample,” the agency said in its announcement. The company’s PCR test is still available for testing individual samples as well.
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Earlier this week, Quest said it has the capacity to perform up to 125,000 molecular diagnostic tests per day, about double its capacity two months ago. It plans to expand that number to 150,000 by the end of this month.
Still, demand for testing continues to grow even faster, pushing the company’s average turnaround time to seven or more days, the company said, and more than 24 hours for high-priority cases—such as hospital patients, preoperative patients in acute care and symptomatic healthcare workers.
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Meanwhile, the FDA recently granted Quest three new emergency use authorizations this week for separate coronavirus assays that allow nasal swab samples to be self-collected at home under the supervision of a clinician via telemedicine.
Each molecular test features the same instructions and process using Quest’s previously authorized home collection kit but are processed using different laboratory hardware, including Roche’s cobas and Hologic’s Panther Fusion and Aptima analyzers.