Countries straining to contain a second wave of COVID-19 are turning to faster, cheaper but less accurate tests to avoid the delays and shortages that have plagued efforts to diagnose and trace those infected quickly.
PCR tests detect genetic material in the virus while antigen tests detect proteins on the virus’s surface, though both are meant to pick up active infections. Another type of test, for antibodies the body produces in response to an infection, can help tell if somebody has had COVID-19 in the past. Antigen tests can also produce more “false negatives”, prompting some experts to recommend they only be used in a pinch.
Various hitches in different countries around testing highlight a conundrum for governments: how to get people back to work while tracing the virus within the population quickly - without running out of supplies.
Reuters