Unless there is widespread testing for COVID-19, experts warn, cases will surge as governments reopen more businesses and public spaces. But there is still a woeful shortage of diagnostic tests for coronavirus infections, because of unprecedented demand for chemicals and supplies. The U.S., for instance, does hundreds of thousands of tests a day, but that number is still far short of the millions of daily assays recommended for a safe return to normal.
Now dozens of researchers in the U.S., Israel and Germany are pursuing a strategy to dramatically increase diagnostic capacity: group tests. By pooling samples from many people into a few groups and evaluating pools rather than individuals, the scientists think they can use fewer tests on more people. This approach could lead to the faster detection of individuals who are unwitting carriers of the disease and an ability to quickly clear others who have not been infected. The strategy has been used in the past to successfully detect cases of HIV, chlamydia, malaria and influenza, and was originally conceived during World War II to test thousands of military personnel for syphilis.
“As long as we have no vaccine, we can only stop the transmission of the virus by testing and isolation of people who are infected,” says Sandra Ciesek, director of the Geothe University Frankfurt’s Institute of Medical Virology in Germany. In mid-February, she was among the first to report that people with no symptoms could spread the virus. Since then, Ciesek has been working on a pooled testing technique to identify asymptomatic carriers. The approach “is trying to do more with the same number of tests,” says Tomer Hertz, a computational immunologist at Ben-Gurion University of the Negev in Israel, who is also developing a batch-testing strategy. There is a caveat, though: as the prevalence of the infection in a community goes up, the ability to save resources through group testing goes down.
Coronavirus Test Shortages Trigger a New Strategy: Group Screening, Marla Broadfoot, Scientific American