KCDC director Jung Eun-kyeong told a briefing on Monday that the current wave began during the May holiday period.
She said the first wave ended in April after the number of daily new cases decreased to around 10 or below for a number of days before trending very slightly upward in early May.
Jung said it was hard to say whether this was a large-scale outbreak but regional outbreaks were occurring and more are expected.
With the number of cases expected to increase in the autumn and winter months, Jung added that health authorities are readying enough beds to deal with a large-scale outbreak.
According to the KCDC, 12,484 people in the country have so far been infected with the virus, with 280 deaths.