The average wait time for a COVID-19 test result in the U.S. has decreased by almost two days since the pandemic struck earlier in the year, but it is still not fast enough to conduct effective contact tracing, a new survey by researchers from Northeastern, Harvard, Northwestern, and Rutgers found. The average turnaround time for test results was as long as 4.4 days in March, but had fallen to 2.7 days by September. Prompt test results are one of the key elements of a successful strategy to contain the spread of SARS-CoV-2, the coronavirus that causes COVID-19, the study said.
Researchers examined more than 8,000 U.S. residents who took a nasal swab test—chosen because it is considered more reliable than rapid antigen tests, says David Lazer, University Distinguished Professor of political science and computer and information sciences at Northeastern, and one of the researchers who conducted the study.
Most testing delays can be traced to a lack of testing supplies, as well as to bottlenecks at several national corporate testing laboratories that didn’t have the capacity to keep up in the pandemic’s early going, Lazer says.
Despite the improving wait times, in many cases the turnaround still isn’t nearly fast enough to identify those who test positive and then trace the people with whom they interacted closely, he says. “Ideally you’d like to work your way through that infection tree with contact tracing, but if it’s a week later or more, then that tree has grown and it’s impossible to even catch up,” says Lazer.