COVID-19 false-negative test results if used too early

In a new study, Johns Hopkins researchers found that testing people for SARS-CoV-2 — the virus that causes COVID-19 — too early in the course of infection is likely to result in a false negative test, even though they may eventually test positive for the virus.

“A negative test, whether or not a person has symptoms, doesn’t guarantee that they aren’t infected by the virus,” says Lauren Kucirka, M.D., Ph.D., M.Sc., obstetrics and gynecology resident at Johns Hopkins Medicine. “How we respond to and interpret a negative test is critical…