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 ...

The three had never met in person, but they shared a common goal: To create an open-source, do-it-yourself PCR test (the gold standard among Covid tests).

The reagents must perform multiple functions, including allowing viral extraction from a nasal swab while preserving lysed RNA to maintain high test sensitivity during RT-PCR.