10 ILCS 5/18-9.2

Where a vacancy in nomination is filled pursuant to Section 7-61 or Section 10-11, the vote by mail votes cast for the original candidate on the first ballot shall not be counted. For this purpose, in those jurisdictions where electronic voting systems are used, the election authority shall determine a method by which the first ballots containing the name of the original candidate may be segregated from the revised ballots containing the name of the successor candidate and separately counted.

Where a vacancy in nomination is not filled pursuant to Section 7-61 or Section 10-11, all votes cast for the original candidate shall be counted for such candidate.