Patients who re-tested positive for coronavirus after being discharged are not contagious, South Korean health officials said Monday.

The Korean Centre for Disease Control (KCDC) made the announcement after conducting a lab analysis of 108 cases and epidemiology investigations on 285 cases to determine whether coronavirus patients should be quarantined for two weeks after being released from hospital. Health officials tested 790 close contacts of the 285 cases who re-tested positive for the virus after recovering, but found no infections linked to the recovered patients.

What this means: Following the announcement, the country’s health officials removed the guideline recommending recovered patients to undergo a further two weeks of quarantine after being released from hospitals and other healthcare facilities.

The Director of the KCDC, Jung Eun-kyeong, said health authorities could not say why some patients were re-testing positive for the virus, but added that experts believed the PCR (polymerase chain reaction) test was detecting pieces of dead virus.

When a positive specimen was isolated and cultivated, coronavirus was not detected in PCR tests, so the experts concluded the virus was not infectious, Jung added.