Medically reviewed by Kate Colby, MPH People with asymptomatic or mild COVID illness generally test negative after nine days, but a polymerase chain reaction (PCR) test can still be positive for up to ...

During the COVID-19 pandemic, a staggering 340 million tests for the virus were supplied across the world by a company based in South Korea that specializes in so-called syndromic real-time polymerase ...

New high-tech Covid-19 tests promise better and earlier detection of the virus—similar to a PCR test. WSJ’s Joanna Stern (and her mannequin clone) tried out the Detect Covid-19 Test and Cue Health ...

As SARS-C0V-2 variants emerged, researchers developed a PCR test that uses molecular beacons not only to diagnose COVID-19 infection, but also to identify the specific variant causing that infection.