The Right Kind of Pooled Testing for the Novel Coronavirus: First, Do No Harm

As with so much else in the COVID-19 pandemic, the United States is so far losing the SARS-CoV-2 testing race. In a growing number of areas of the country, as well as at educational and work sites, testing and obtaining timely results cannot keep pace with demand. Because the effort and cost of so much testing is considerable, and because some testing supplies are still scarce, it's important to conduct tests as efficiently and cost-effectively as possible. If the nation is to overcome its testing challenges, it may have to turn to more pooled testing, in which a number of samples are combined and processed as if they were a single specimen. Some pooling of tests is already under way in other countries; the US Department of Health and Human Services (HHS) is reportedly considering it, and in mid-July 2020, the US Food and Drug Administration (FDA) gave the commercial laboratory company Quest Diagnostics the green light to pool samples of its diagnostic test for the virus.1 But pooling tests in any fashion will not be a solution; in fact, there are right ways and wrong ways to undertake pooling. The protocol currently being evaluated by the HHS, and to be used by Quest, is the so-called Dorfman protocol, a highly touted procedure initially designed to test the urine of Army recruits for syphilis during World War II. Under this approach, for example, 10 samples may be pooled together; if the pool tests negative, all samples within the pool will be declared negative. If the pool tests positive, that will suggest that at least one sample in the pool is positive, so each sample will be tested individually to identify the positive samples.