Dr Manali Mukherjee, an assistant professor in the Division of Respirology, Department of Medicine, McMaster University, and a translational scientist affiliated with the Research Institute of St. Joseph’s Healthcare Hamilton, talks about the immunologic background of post–acute COVID sequelae (PACS), also called long COVID. The webinar, chaired by Dr Madeleine Verhovsek and Dr Dawn Bowdish, was recorded at the Chair’s Medical Grand Rounds on September 22, 2022.