While briefing to the media, Jeong Eun-kyeong, director of the Korea Centres for Disease Control and Prevention said that the virus may have "reactivated" in the patients rather than them becoming reinfected.
It is, however, unclear that how and why it has happened in all of them again with an epidemiological investigation underway said health officials.
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According to the Johns Hopkins database, South Korea has recorded, 10,450 cases of novel coronavirus with 208 deaths and 7,110 recoveries.
On Friday, the KCDC has reported 27 new cases of Covid-19, the lowest number since late February. It has also confirmed 7 latest deaths from the virus.
Whether a person can become infected with COVID-19 twice has apparently been unknown since the outbreak of the pandemic. The Centers for Disease Control and Prevention says that the body's immune response, including how long someone is immune to the virus, "is not yet understood."
The agency said patients who had been diagnosed with a virus similar to COVID-19 "are unlikely to be reinfected shortly after they recover, but it is not yet known whether similar immune protection will be observed for patients with COVID-19."
Globally, more than 1.65 million cases of the coronavirus have been reported and more than 100,375 people have lost their lives. Nearly 368,670 people have recovered from it.