On Sept. 24, a positive COVID-19 case was reported at South High School in Cohort A.
The person was last in the building on Sept. 17, the school district said.
The school district said they are working with the Sheboygan County Division of Public Health to identify and notify parents of any students and staff who may have come into close contact with the student who tested positive.
The letter said those who had close contact are at risk of getting sick and will be instructed to quarantine (stay home). Cleaning and disinfecting the affected classrooms to control the spread of illness is also being completed.