South Korean officials say analysis of samples from recovered Covid-19 patients show all had formed neutralizing antibodies, but almost half still showed viral genetic material, Korean Centers for Disease Control (KCDC) Director Dr. Jung Eun-kyeong said at a press briefing Wednesday.

She added that these patients are likely not contagious.

“One can presume that depending on the patient, the virus can stay for different lengths of periods in the body without being completely removed even after neutralizing antibodies had formed. Additional study is underway,” Jung said.

About the analysis: The KCDC conducted analysis on 25 recovered patients to determine whether the Covid-19 virus could be detected. 25 patients had formed neutralizing antibodies against the virus, and 12 patients tested positive for Covid-19. When the samples from the 12 patients were cultivated the results were negative, Jung said.

Samples were taken from 39 cases that retested positive and so far 6 samples did not cultivate the virus. Examination on 33 other samples is ongoing.