Seoul, Gyeonggi-do Province, Gwangju City to the southernmost city of Busan.
Small cluster infections stemming from local transmissions are once again rising sharply throughout the country.
Of 56 new cases reported on Thursday, 47 were transmitted locally,the highest domestic number in over 40 days.
The Seoul metropolitan area accounted for more than half the cases.
Eleven cases have been traced to meetings held this month by employees of the fast-food chain Lotteria in at least eight parts of Seoul.
Others came from nursing homes and churches,places that are seeing constant infections.
The virus has permeated schools as well.
Five high school students contracted the virus in Gyeonggi-do Province, transmitting it to their friend and families.
Students in Ulsan and Busan have also tested positive.
Health authorities say the situation is more serious than ever and could be worse than the Itaewon cluster infections, which resulted in 277 cases over a short period.
"This spread is more concerning than the Itaewon cluster. This is not from a single source, but more of a silent spread with no symptoms and it's happening simultaneously all over the country in close gatherings such as at churches, workplaces, markets and schools."
In the past two weeks, cases with uncertain transmission routes have jumped to 13.4 percent.
That's way over the 5 percent standard for the lowest social distancing level.
Health authorities say they could raise the social distancing level a notch to level twojust a hundred days after the level was lowered to one in early May.
The Seoul city government has also handed down an adminstrative order banning assemblies scheduled for National Liberation Day that would've seen some 220-thousand people come together on Saturday.
With the long vacation period starting Friday, health authorities are advising people to refrain from gatherings of any size and to wear a face mask at all times when outside.
Choi Jeong-yoon, Arirang News.