Key Points

Question  What were the burden and transmission patterns of influenza, mumps, and hepatitis A in US Immigration and Customs Enforcement detention facilities from 2019 to 2023, and what risks did they pose to detained migrants and staff?

Findings  This case series of 20 facilities found that influenza (2035 cases), mumps (252 cases), and hepatitis A (486 cases) were all prevalent with varying seasonality and multiple facility outbreaks, reflecting the risk profiles for respiratory and enteric infectious diseases of persons entering detention.

Meaning  On the basis of these findings, decongregation, control of facility crowding, and vaccination programs are recommended approaches to reduce transmission risks for incarcerated migrants and facility employees.

Abstract

Importance  Migrants detained by US Immigration and Customs Enforcement (ICE) are at risk of preventable infections from crowding and limited health care. Postpandemic risk remains unclear as detention increases.

Objective  To assess epidemiological patterns of 3 vaccine-preventable diseases within ICE facilities.

Design, Setting, and Participants  This case series study examined data from January 2019 through October 2023 from ICE facilities managed by ICE Health Services Corp during the study period. All cases of influenza, mumps, and hepatitis A among persons detained in reporting ICE facilities were included.

Exposure  Diagnosis of influenza, mumps, or hepatitis A during ICE detention.

Main Outcomes and Measures  The primary outcomes were monthly case counts and estimated case rates (per 100 000 person-months), outbreak occurrence and duration, and seasonal and geospatial patterns. Outbreaks were defined as 3 or more cases within a facility over at least 1 month. Seasonal variation was assessed through variations in mean monthly case rates across years with analysis of variance, and Tukey tests were used to compare monthly pairwise permutations for statistical significance. Geospatial trends were evaluated using global and local Moran I analyses of annual facility-level case rates.

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