[zipping]

https://www.livescience.com/coronavi...positives.html

Recovered patients who tested positive for COVID-19 likely not reinfected

Rather, the method used to detect the coronavirus, called polymerase chain reaction (PCR), cannot distinguish between genetic material (RNA or DNA) from infectious virus and the "dead" virus fragments that can linger in the body long after a person recovers, Dr. Oh Myoung-don, a Seoul National University Hospital doctor, said at a news briefing Thursday (April 30), according to The Korea Herald.

These tests "are very simple," said Carol Shoshkes Reiss, a professor of Biology and Neural Science at New York University, who was not involved in the testing. "Although somebody can recover and no longer be infectious, they may still have these little fragments of [inactive] viral RNA which turn out positive on those tests."

To determine whether or not someone is harboring infectious virus or has been reinfected with the virus, a completely different type of test would be needed, one that is not typically performed, Reiss said. Instead of testing the virus as it is, lab technicians would have to culture it, or place that virus in a lab dish under ideal conditions and see if it was capable of growing.

Patients in South Korea who re-tested positive had very little to no ability to spread the virus, according to the Korea Centers for Disease Control and Prevention, the Korea Herald reported.