Prevention of infectious diseases in refugee and immigrant children presents special challenges because of the diseases to which these children may have been exposed and the different immunization practices in their native countries. In addition, other aspects of providing care (including testing for exposure to environmental toxins, such as lead) to immigrant, refugee, homeless, and immigrant children should be considered.² In 1996, Congress amended the Immigration and Nationality Act (INA), requiring immigrant visa applicants to provide "proof of vaccination" with at least the first dose of ACIP-recommended vaccines before entry into the United States. Although these regulations apply to most immigrant children entering the United States, internationally adopted children who are 10 years of age or younger may obtain an exemption from these requirements. Adoptive parents are required to sign a waiver indicating their intention to comply with the ACIP immunization requirements within 30 days after the child's arrival in the United States. Refugees are not required to meet immunization requirements of the INA at the time of initial entry into the United States but must show proof of immunization when they apply for permanent residency, typically 1 year after arrival. However, in outbreak settings, selected refugees bound for the United States are immunized in their country of origin before arrival in the United States. Clinicians should review the CDC Refugee Health Web site (www.cdc.gov/ncidod/dq/refugee/index.htm) for information about which refugee populations currently are receiving immunization outside the United States. Information about immunization requirements for immigrants is available at www.cdc.gov/ncidod/dq/panel_vaccine_2007.htm.

Children who have resided in refugee processing camps for a few months often have had access to medical and Treatment services, which may have included some immunizations. However, these children almost universally are incompletely immunized and often have no immunization records. For refugee children whose immunizations are not up-to-date, as documented by a written immunization record, vaccines as recommended for their age should be administered (see Fig 1.1-1.3). For children without documentation of immunizations, a new vaccine schedule may be initiated. Alternatively, measurement of antibody concentrations to diphtheria, tetanus, measles, mumps, rubella, varicella, and poliovirus (each serotype) as well as anti-HBs, HBsAg, and antibody to hepatitis B core antigen (anti-HBc), if from an area with endemic hepatitis B infection, may be considered to determine whether the child needs additional immunizations or initiation of the immunization schedule appropriate for that child's age (see Table 2.17, Approaches to the Evaluation and Immunization of Internationally Adopted Children). Although many children will have received DTP, poliovirus, measles, and hepatitis B vaccines, most will not have received Hib, pneumococcal, hepatitis A, rubella, mumps, and varicella vaccines. Measles antibody may be measured to determine whether the child is immune; however, many children may need a dose of mumps and rubella vaccines, because these vaccines are not given routinely in developing countries. A clinical diagnosis of rubella without serologic testing should not be accepted as evidence of rubella immunity. Varicella vaccine is not administered in most countries, and history of varicella infection may be unavailable or unreliable in these populations; therefore, children should be immunized for varicella or have antibody testing performed.

All refugees and immigrants from areas with endemic hepatitis B infection, particularly Asia and Africa, should be screened for hepatitis B with serologic tests for HBsAg, anti-HBs, and anti-HBc. A child who has positive test results for HBsAg has active infection and may be defined as a chronic carrier if the HBsAg persists for longer than 6 months. Most children who are HBsAg carriers are asymptomatic. Therefore, screening is important to identify children who need follow-up and management and to limit transmission of disease. Transmission risks should be minimal among children in the United States because of universal infant HBV immunization programs. However, unimmunized adult caregivers should be given hepatitis B vaccine if they are susceptible and HBIG if they have had a significant exposure to blood of a carrier (see Hepatitis B). Serologic screening of all pregnant refugees and immigrants for HBsAg is imperative to identify women whose infants need passive as well as active immunoprophylaxis.

Tuberculosis and HIV infection are important public health concerns, because many refugees and immigrants come from countries with high prevalences of tuberculosis and HIV infection. Tuberculosis cases in foreign-born people now account for more than 50% of all tuberculosis cases in the United States. Although tuberculosis rates have decreased among children born in the United States in the last decade, rates remain high among children from developing countries. The overseas screening requirements for tuberculosis for immigrants and refugees bound for the United States underwent a major revision in 2007, including tuberculosis screening for all people, and are in the process of being implemented. Information about the screening and implementation is available at www.cdc.gov/ncidod/dq/panel_2007.htm. The risk of HIV infection among refugees and immigrants depends on the country of origin and on individual risk factors, especially among vulnerable refugee populations. As part of the required overseas medical assessment, HIV testing is performed on all immigrants and refugees 15 years of age and older. Children younger than 15 years of age are tested for HIV if history or examination raises concern about possible HIV infection (eg, maternal history of HIV infection, history of rape or sexual assault). The decision to screen children for HIV after arrival in the United States should depend on history and risk factors (eg, receipt of blood products, maternal drug use), physical examination findings, and prevalence of HIV infection in the child's country of origin (www.who.int/hiv/countries) . If there is a suspicion of HIV infection, testing should be performed before administration of live vaccines.