The number of cases of the norovirus that causes diarrhea and vomiting has increased five times in the past two months.

According to the Korea Disease Control and Prevention Agency on Sunday, a total of 268 cases of norovirus infections were reported in the last week of December at 206 hospitals.

This represents a five-fold increase in two months compared to 49 cases in the second week of November last year.

The number of norovirus cases was about 50 until mid-November before exceeding 200 in the third week of December, with infants and children aged six and under accounting for about half of the total.

Norovirus is an infectious disease that occurs year-round, but most patients are diagnosed during the winter and early spring.

Norovirus is mainly transmitted when consuming water or food contaminated with norovirus and can also spread from person to person through contact with a patient. There is no preventive vaccine for norovirus, so good hygiene is important to prevent infection.