The Illinois Department of Public Health is adopting a new definition of what constitutes a COVID-19 outbreak in schools, which will result in a fewer number of reported outbreaks, according to information provided by health officials.
Under guidance from the Council of State and and Territorial Epidemiologists, an outbreak will be defined as either multiple cases comprising at least 10% of students, teachers or staff within a "core group" or at least three cases within a specified "core group," IDPH stated in a news release.
A "core group" is defined as individuals who were together during an exposure period, which could include those inside a classroom, members of a sports team, performing arts or other groups.
Previously, the Centers for Disease Control and Prevention recommended that two cases associated within a school would constitute an outbreak, health officials said.
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“This change in criteria will continue to identify outbreaks and help prevent further spread, but also help rule out outbreaks that are not associated with the school," said IDPH Director Dr. Ngozi Ezike, noting the change was recommended by the CDC.
To be considered part of an outbreak, cases must meet the criteria for a probable or confirmed school-associated case with a positive test result, or the start of symptoms within 14 days of each other, according to IDPH.
The individuals must be close contacts with each other while in school and not an outside setting. Furthermore, the cases must be "epidemiologically linked to the setting," meaning they were at the same place at the same time.