The Death of the Mirror Universe Dr. McCoy

In the Mirror Universe, Dr. Leonard McCoy died in the year 2269 of the fatal disease known as xenopolycythemia, indicating that, in the Mirror Universe, either the ISS Enterprise never encountered Yonada, or they simply destroyed the vessel because it was hostile. Dr. McCoy was succeeded as the ISS Enterprise's chief medical officer by Jabilo M'Benga, who continued to serve in that position until at least 2287.