‘Not a magic bullet’: Experts discuss pros and cons of pooled testing for COVID-19
Following the first FDA approval of a COVID-19 test for pooled sampling, experts discussed the pros and cons of the strategy during a briefing hosted by the Infectious Diseases Society of America.
Melissa B. Miller, PhD, director of the University of North Carolina Medical Center’s clinical molecular microbiology laboratory, emphasized that although pooled testing is “not a magic bullet” for improving testing capacity, it can be useful under certain circumstances and for measuring disease prevalence.
The recent FDA approval allows for the use of Quest Diagnostics’ SARS-CoV-2 rRT-PCR to test up to four individual COVID-19 swab specimens at a time.
Miller noted that similar pooled approaches have been successful for HIV RNA testing, but a greater pool size may increase the risk for false-negative test results. A recent virtual Town Hall held by the American Lung Association also addressed testing-related issues.
“Pooling isn’t perfect, but the alternative is that fewer people get tested,” Miller said.
Romney M. Humphries, PhD, director of Vanderbilt University Medical Center’s clinical microbiology laboratory, said there are several considerations that need to be accounted for when considering pooled testing, such as the availability of skilled lab workers, and that it is “not a simple test” to perform.
She also noted that regulatory roadblocks may be an issue, and robotics may be a useful tool for increasing the overall capacity for pooled testing. Humphries emphasized that the size of pooled samples will be important to avoid diluting results.
“We don’t want to be watering down these samples too much, in particular for patients that are more critically ill,” Humphries said.
Miller said COVID-19 testing supplies currently have a “supply-demand problem,” further hindering test capacity and making alternative testing strategies a necessity.
“We’re asking for more than can actually be produced,” Miller said. “To give you an example of the scope of this, we are even running out of things in other areas of the laboratory as some of the production lines get switched to either make viral transport media or other supplies we need to keep our tests running. We’re having to vie for supplies to do regular microbiology.”