Of the new cases, 434 were local transmissions and only 7 were imported cases.
There was one more death, raising the death toll to 313.
The 441 new cases on Thursday is the highest daily number since March 7, when the country reported 483 cases.
The number of new cases has been on the rise again this week after briefly dropping below 300 on Monday and Tuesday.
The country has now seen 14 days in a row of new cases in the triple digits.
Of the 434 locally transmitted cases, more than 70 percent have been identified in the capital area, home to half of the country’s population.
Seoul added 154 more cases, its largest daily virus tally, while the surrounding Gyeonggi-do Province and city of Incheon reported 100 and 59 cases, respectively.
However, authorities said that the source of infection of at least 30 percent of the newly infected patients couldn’t be detected, raising the possibility of more infections.
The Health Ministry has urged the public to refrain from heading out, as this week is the last chance to bring the virus back under control.
“I hope the public remembers our experience of overcoming the nation’s largest cluster infection through social distancing. I urge the public to refrain from gatherings and meetings.”
The Health Ministry says if the situation does not improve this week, it will consider all options including raising the social distancing level to three, which would practically halt all economic and social activities in the nation.
Kim Mok-yeon, Arirang News.