South Korea confirmed 56 new cases of the coronavirus on Thursday, raising the total to 14,770.
This is the second straight day the number of new infections has been higher than 50.
A majority of the new cases were transmitted locally, attributed to new cluster infections in the Seoul metropolitan area, and to churches, schools and nursing homes.
According to the city government, some of the cases have been traced to meetings held earlier this month by employees of the fast-food chain Lotteria in at least eight parts of Seoul.
"In fact, right now, I think the situation is serious. The number of confirmed cases is rising during the summer vacation season. Things are volatile right now especially in Seoul and the surrounding region."
The health authorities warned that they could have to raise the level of social distancing measures from the current level one to to level two on the three-tier system.
The level-two social distancing measures include a ban on gatherings of more than 50 people indoors and 100 people outdoors.
Also, fewer people would be able to attend school in person and spectators would not be able to attend sports events.
Regarding vaccines, the authorities said clinical trials on three locally developed candidates are expected to begin this year.
Those are being developed by the companies SK Bioscience, Genexine and GeneOne Life Science.
Kim Ji-yeon, Arirang News.