745 ILCS 10/6-104

(a) Neither a local public entity nor a public employee is liable for an injury resulting from the policy decision to perform or not to perform any act to promote the public health of the community by preventing disease or controlling the communication of disease within the community if such decision was the result of the exercise of discretion vested in the local public entity or the public employee, whether or not such discretion was abused.

(b) Neither a local public entity nor a public employee is liable for an injury caused by an act or omission in carrying out with due care a decision described in subdivision (a).