In 2019, the US Immigration and Customs Enforcement (ICE) agency detained 510 854 migrants.1 Detention centers have poor living standards and environmental crowding that may facilitate infectious disease transmission.2,3 We documented outbreaks of influenza, varicella, and mumps among involuntarily detained migrants.
We obtained data on clinical influenza, varicella, and mumps cases among migrants in a subset of ICE detention centers from January 1, 2017, to March 22, 2020, through a formal request to ICE and the Department of Homeland Security. We received deidentified individual-level case data for ICE detention centers where the ICE Health Service Corp is the facility medical authority and uses the ICE electronic health record system (22 of 315 centers).2 Data were obtained by ICE officials through chart review using International Classification of Diseases (ICD) diagnosis codes alone. We analyzed summary statistics for infections by date, age, and facility. We defined an outbreak as 3 or more cases linked in time and place over a 1-month period, with outbreak duration defined by occurrence of 3 or more cases per contiguous month. This project was considered exempt non–human subjects research by the institutional review board at the University of California, San Francisco. Analytic code (R version 4.0.2) and data are available from the authors.