SEOUL, April 17 (Xinhua) -- The number of South Koreans who retested positive for the COVID-19 after having been released from quarantine with full recovery rose to 163, the health authorities said Friday.

The number of those who tested positive again for the virus came in at 163, taking up 2.1 percent of the combined 7,829 patients who have been discharged from quarantine, according to the Korea Centers for Disease Control and Prevention (KCDC).

It took one day to 35 days for those released from quarantine to retest positive for the virus. It took 13.5 days on average.

No case has been reported yet that those who retested positive infected others.

An epidemiological and clinical investigation was underway into those who tested positive again for the COVID-19.

The KCDC has seen a higher possibility for the virus remaining in certain cells to be reactivated, rather than people being re-infected, as they retested positive in a relatively short period of time after being released from quarantine.

In the latest tally, South Korea reported 22 more COVID-19 cases for the past 24 hours, raising the total number to 10,635. The daily caseload hovered below 30 for the fifth consecutive day.