On 9/3/2021, the governor of Illinois issued Executive Order 2021-22 containing COVID-19 vaccine requirements for health care and school personnel. These individuals include all healthcare workers, nursing home employees, P-12 teachers and staff, and higher education personnel and students. The order also places vaccine mandates upon state employees who work at state-owned or operated congregate facilities. Namely, this includes facilities operated by the Illinois Departments of Human Services, Corrections, and Juvenile Justice.
Exemptions may be granted along with a weekly COVID-19 testing requirement for individuals with medical contraindications or objections based upon sincerely held religious beliefs, practices, or observances.
This order has been re-issued in its entirety several times by subsequent executive orders.
https://coronavirus.illinois.gov/resources/executive-orders/display.executive-order-number-22.2021.html - text of the executive order.