Why some South Koreans tested positive twice

In South Korea, some recovered patients have tested positive again for the new coronavirus.And scientists are trying to work out why. South Korea had reported 141 such cases as of Thursday (April 16).They're worrying, because re-infection goes against the hope that populations will develop immunity.Luckily, re-infection is unlikely, say the Korea Centers for Disease Control and Prevention.Some sort of relapse and reactivation looks more plausible. Meaning the virus goes into a dormant state for