On April 8, 2020, this report was posted online as an MMWR Early Release.Isaac Ghinai, MBBS1,2; Susan Woods1; Kathleen A. Ritger, MD1; Tristan D.
McPherson, MD1,2; Stephanie R. Black, MD1; Laura Sparrow1; Marielle J. Fricchione, MD1; Janna L. Kerins, VMD1; Massimo Pacilli, MPH1; Peter S.
Ruestow, PhD1; M. Allison Arwady, MD1; Suzanne F. Beavers, MD3; Daniel C. Payne, PhD4; Hannah L. Kirking, MD4; Jennifer E. Layden, MD, PhD1 (View author affiliations)Early reports of person-to-person transmission of SARS-CoV-2 have been among household contacts, health care workers, and within congregate living facilities.Investigation of COVID-19 cases in Chicago identified a cluster of 16 confirmed or probable cases, including three deaths, likely.