An Assessment of Varicella Susceptibility Among U.S. Immigration and Customs Enforcement (ICE) Detainees

BACKGROUND: U.S. Immigration and Customs Enforcement (ICE) is responsible for enforcing federal immigration laws, including the detention of unauthorized aliens during immigration proceedings. ICE detainees are unlikely to have medical or vaccination records with them when they are brought into ICE custody, and their countries of origin often lack immunization programs including varicella. An outbreak of varicella represents a public threat to detainees, exposed employees, and the public. Given the 21 day period of cohorting with restricted movement, and challenges with preventing disease transmission in a congregate setting, varicella cases and potential transmission are a priority concern for ICE and detention facility operations. This project assessed serological evidence of immunity to varicella among ICE detainees in a large detention center in Southern California to inform vaccination policies and reliability of self-reported history.

METHODS: We obtained a convenience sample from all detainees who received a routine medical evaluation within 14 days of arrival to the detention facility. Detainees with known medical contraindications to receive varicella vaccination or who were unable to reliably consent were excluded from recruitment. ICE health staff abstracted patient demographics and medical information from patient electronic health records and administered a brief questionnaire to obtain a patient’s history of varicella and varicella vaccination, attitudes toward immunizations, and household composition. We calculated univariate descriptive statistics for demographic characteristics, serologic varicella immunity and HIV status among project participants using Epi Info 7.

RESULTS: As of January 5, 2015, 283/400 individuals have been recruited. Among the 265 (93.6%) participants with serologic laboratory testing, 13.2% (n=35) were not immune to the varicella virus. The majority of participants with laboratory results were male (n=189, 71.3%) and originated from Mexico and Central America (n=197, 74.3%). 

CONCLUSIONS: Preliminary results indicate that the ICE detainee population in this setting has an overall varicella IgG seroprevalence below the threshold needed to prevent an outbreak. Inclusion of varicella vaccination in routine ICE detention preventive practices might be indicated. However, further data regarding HIV seroprevalence, reliability of self-reported history, detainee subpopulations at highest risk of varicella susceptibility to target, and vaccine acceptance and delivery systems are necessary to ensure a safe and feasible vaccination program.