The Case for Mass-Scale COVID-19 Testing

As schools and businesses struggle to reopen in the midst of a global pandemic, institutions and test developers have been working on strategies to mass produce and deploy rapid tests, pool samples and step up contact tracing for COVID-19. These efforts wouldn’t necessarily replace standard polymerase chain reaction (PCR) diagnostic testing, but instead offer a way to repeat tests on a mass scale, enabling routine activities to take place safely.

Some in the clinical lab community worry that urgency is replacing accuracy in the national push to test large masses of people. As of now, the supply chains and tests to build a national testing strategy don’t exist, Alexander Greninger, MD, PhD, assistant director of the University of Washington’s Medicine Clinical Virology Laboratory and an assistant professor of laboratory medicine, told CLN Stat. No performance characteristics or clinical trials for these tests have been established, he continued. “All of a sudden we seem to care less about sensitivity or regulation.”

PCR testing is about 98% accurate and returns very few false positives, but in practice hasn't been returning results quickly enough. In one analysis, investigators reported that weekly screenings with a variety of less sensitive PCR tests could avoid outbreaks by delivering immediate results and having positive individuals self-isolate. Some jurisdictions have resorted to pooling PCR tests, which captures more test results and helps conserve supplies, according to one news report. Pooling, however, “is only a stopgap. It works best for diseases that are relatively rare, such as HIV and syphilis. If a disease is too common, then the work of pooling—the laborious mixing and remixing of samples—is more work than it’s worth,” according to another news report in the Atlantic.

Such dilemmas have spawned new innovations. Ginkgo Bioworks, for example, leveraged its Illumina gene-sequencing machines to create a rapid test that identifies 98 targets on SARS-CoV-2 through nasopharyngeal, oropharyngeal, and mid-turbinate nasal swabs. According to the Atlantic, Gingko, under a federal grant with its start-up partner Helix could be testing up to 1 to 3 million samples daily by the end of the year at several facilities.