The cases were among 462,916 test results submitted to the Illinois Department of Public Health.
The seven-day testing positivity rate is at 5.3%, health officials said.
State health officials said more than 77% of Illinois adults have received at least one vaccine dose and more than 60% are fully vaccinated.
Since the beginning of the pandemic, Illinois has recorded 1,482,369 cases and 23,717 deaths tied to COVID-19.
As of Thursday night, 2,000 Illinoisans were hospitalized with COVID-19, with 468 needing intensive care and 234 on ventilators.