Active cases of COVID-19 were identified by local public health officials Wednesday at 4 schools in the London District Catholic School Board system. One case at Our Lady Immaculate School in Strathroy. The schools will remain open. If you do not receive a letter indicating the public health unit has identified your child as a close contact, your child is not considered to be at risk. Health units investigate cases to identify close contacts and follow up directly to provide specific testing advice.