From 2000 to 2009, nearly 200,000 children were adopted from outside the United States.1 Although numbers have decreased over the past few years, an average of approximately 18,500 children were adopted each year from 2005 to 2009. Medical status of these children is generally not optimal, as many have experienced abandonment and have been residents of large group facilities (eg, orphanages) with limited resources. These children may have experienced significant perinatal stresses, including exposure to tobacco, alcohol, and drugs, and low birth weight. Given the living environment, nutrition has likely been compromised and environmental stimulation has been limited, while infectious disease risk has increased.
Hostetter et al., in a seminal study, reported that 185 infectious conditions were found among 293 international adoptees.2 These conditions included active tuberculosis, active hepatitis B, intestinal parasites, and bacterial gastroenteritis. More recently, Murray et al. reviewed the prevalence of infectious diseases among international adoptees and provided recommendations on screening and management.3
Although many of the more prominent infections are not vaccine-preventable (eg, intestinal parasites), there have recently been transmitted cases of hepatitis A and measles among contacts of international adoptees,4–6 and the risk of other vaccine-preventable conditions remains of concern. It is also rare that internationally adopted children are fully immunized and up-to-date with vaccines recommended for U.S. children by the Advisory Committee on Immunization Practices (ACIP).7
The countries of origin of international adoptees have varied over time, but during the past 5 years, the largest number of adoptees arrived from China, Russia, Guatemala, Ethiopia, and South Korea.7 Immunization practices vary by region and country, and documentation can be missing or difficult to interpret. Although some vaccines with inadequate potency are used in other countries, most vaccines available worldwide are produced with adequate quality-control standards and are reliable. However, information about storage, handling, site of administration, vaccine potency, and provider generally is not available.8 In some countries, fewer doses may be administered to decrease costs of vaccines. Despite these concerns, the American Academy of Pediatrics (AAP) and the ACIP state that any documented vaccine that is administered at the age and intervals recommended by the ACIP can be considered valid.8,9
Even when written records are available, however, there may be some concern about the accuracy of documentation or the appropriateness of the vaccine. For example, documentation of doses administered before the birth of the child or in clockwork regularity is suggestive of possible falsification of records.
There is also concern about the effectiveness of immunizations if timing is discrepant from that recommended in the United States.7 Because of the higher risk of vaccine-preventable infectious diseases in many countries of origin for international adoptees, the recommended immunization schedule in those countries may differ from that in the United States, with vaccines administered earlier and with a shorter interval before re-vaccination. The effect of this, as well as the effect of malnutrition and concomitant medical illnesses, upon immunologic response to vaccination is not always clear or readily predicted.
There are some general schedule differences between the United States and the countries of origin for most international adoptees (see Table).10 In China, the recommended schedule begins at birth with hepatitis B vaccination. Subsequently, initial polio vaccination is performed with oral polio vaccine starting at 2 months and is administered on a monthly basis until 4 months. Then a booster is given at 4 years. Immunization with diphtheria/tetanus/pertussis (DTP) begins at 3 months of age and is administered monthly until 5 months, with a subsequent booster at 18 to 24 months. Measles and rubella vaccines are administered at 8 months, with a booster at 18 to 24 months. Although these intervals are acceptable with catch-up immunizations, they are not the recommended intervals for primary immunization of infants in the United States.
Table. Recommended Immunization Schedules by Country
Similarly, in Russia, vaccines are administered at 6-week intervals, and mumps and rubella vaccines are not included with the measles vaccine given at 12 months of age. In Ethiopia, immunizations are recommended to begin at 6 weeks and are administered at 4-week intervals. Measles is given as a single vaccine administered at 9 months of age. Schedules in Guatemala and South Korea follow that of the United States, with regard to administered vaccines. At this time, most countries of origin for international adoptees do not administer vaccines against Haemophilus influenzae type b, Streptococcus pneumoniae, hepatitis A, varicella, or rotavirus.
Diphtheria, Tetanus, and Pertussis
In the United States, immunization against diphtheria, tetanus, and pertussis is provided in a combination vaccine using an acellular pertussis component (DTaP), rather than whole cell vaccine (DTP).11 As indicated in the Table (page 518), DTP is generally initiated at an appropriate age (6 weeks to 3 months), but is often accelerated (4 weeks between doses) relative to the recommended U.S. schedule.7 Immunity against diphtheria and tetanus toxins can be confirmed in children older than 6 months if antitoxin antibodies exceed 0.1 IU/mL.
In a recent study evaluating antibody titers relative to the number of documented vaccine doses administered to international adoptees, it was found that 94.6% had evidence of immunity to diphtheria when three or more doses of vaccine were documented.12 The corresponding percentage for tetanus was 87.2%. There was some variation among countries, more so for tetanus than for diphtheria. For example, protective immunity for tetanus, given documented administration of three or more doses of vaccine, was 76.4% in China and 94.9% in Guatemala. In contrast, in a study from the Netherlands, only 38.2% of Chinese adoptees and 67.2% of children from other countries had protective immunity against diphtheria, although “most children had received a complete course of immunization.”13
Schulpen et al. found that only 60% of children adopted from China had protective immunity in the context of documented immunization.14 In a study of international adoptees in Italy, good rates of protective immunity were found for diphtheria (95.7%) and tetanus (91.4%), but poor protection against pertussis (32.6%) was reported.15 It should be pointed out, however, that there is no accepted standard measure of immunity to infection or disease caused by Bordetella pertussis. In a larger study recently conducted in Spain, rates of protective immunity of international adoptees were 92% and 76%, respectively, for tetanus and diphtheria.16
Given the variability of protective immunity in the context of documented immunizations, it is reasonable to verify protective immunity by serological testing. If antibodies to diphtheria and tetanus toxins are above protective levels, age-appropriate immunization should be completed with DTaP or diphtheria/tetanus (dT).7 If both antibody titers are below the protective level, the child should be completely re-immunized per the ACIP catch-up immunization guidelines.7 If one of the titers is less than 0.1 IU/mL, but the other is above the protective level, it is reasonable to provide one dose of vaccine and re-measure antibody levels in 1 month. A large increase in both titers most likely confirms the presence of prior immunizations.
In most countries from which children are internationally adopted, oral polio vaccines (OPV) rather than inactivated polio vaccines (IPV) are used. As with DTP, immunization with polio is generally initiated at an appropriate age (6 weeks to 3 months) but is often accelerated (4 weeks between doses) relative to the recommended U.S. schedule.17
Protective levels of neutralizing antibody to polio can be measured in children older than 6 months. Titers must be measured for all three polio serotypes. Protective immunity in the context of three or more doses of polio vaccine is generally lower than that seen with DTP and varies significantly by polio serotype. For example, in a study from Italy, overall protective immunity was 58.3% for polio type 1; 82.4% for polio type 2; and 51.9% for polio type 3; only 38.5% had adequate antibody response against all three types.15
Variability was also seen by country. For example, for polio type 1, protective immunity (with three or more doses of vaccine) was 40.4% in China; 53.7% in Guatemala; and 69.7% in Russia. A study from the Netherlands also found that children from China had less overall protection to polio in comparison with children from other countries (66.5% versus 80%).13 In contrast, in Spain, 89% to 96% of internationally adopted children were found to be protected against polio types 1–3 when considering those with and without documented vaccination; 73.2% of children had vaccination records were considered valid, and 86% were fully protected against all three polio types.16
Given the variability in protective immunity, even in context of an adequate number of documented doses of vaccine, it is reasonable to document the presence of protective antibody titers for polio types 1–3 in all children older than 6 months. Those children without protective immunity to all three serotypes should complete the recommended U.S. immunization schedule7 if fewer than three doses of OPV or IPV were received. Those who received three or more vaccines, but have inadequate protective levels to one or more serotypes, should be completely re-immunized. Finally, if no documented records are available, but children have protective titers to all three serotypes, it is reasonable to administer a final booster dose of IPV at age 4 to 6 years.
Most countries from which international adoptees arrive uniformly recommend hepatitis B vaccination starting shortly after birth. Although schedules vary across countries, they are generally consistent with the ACIP recommendations.18 If documentation is available, most adoptees will have documentation of adequate and appropriate immunizations. Most children will also have lab testing before adoption to measure the presence of a protective immune response or to detect active or past hepatitis B infection. Acute or chronic hepatitis B infection can be documented in 1% to 5% of adoptees,18 and up to 10% of adoptees with documented immunization (two or more doses of vaccine) do not have protective immunity.12
Van Schaik et al.13 found that only 76.5% of children had protective immunity against hepatitis B (numbers were similar for children from China and those from other countries). Viviano et al.15 found three of 41 children without documentation of immunization to be surface-antigen-positive (7.3%); while 17.2% of those with documented immunization had no evidence of serologic conversion (ie, negative surface antibody). In Spain, Cilleruelo et al.16 found that 24% of children did not have evidence of protection against hepatitis B. In the large study of Stadler et al.,19 31% of 1,228 patients did not have protective immunity (regardless of immunization status). Of these children, 50% had documentation of two or more doses of hepatitis B vaccine.
Given that a relatively significant percentage of children with documented hepatitis B vaccination have no protective immunity, it is recommended that all international adoptees receive serological evaluation for hepatitis B (including surface antigen, surface antibody, and core antibody) at initial evaluation and at 6-month follow-up, if the initial studies show no infection or protective immunity.
Hepatitis A vaccination is recommended at 18 months in the immunization schedule for China. However, is not a recommended vaccine in other primary countries of origin for international adoptees, although in many of these countries, hepatitis A infection is endemic. Infection in young children is often asymptomatic but can be associated with significant illness in adult contacts. Serologic testing should be performed on all internationally adopted children for IgM (evidence of acute infection) and IgG (evidence of past infection or immunization).
Because of the association of newonset hepatitis A infection among contacts of international adoptees, with adults having a higher likelihood of symptomatic illness, it was recently recommended that close contacts (not just travelers to the area of endemicity) of newly arrived international adoptees receive hepatitis A vaccine.20 Acute or past hepatitis A infection in the child eliminates need for vaccination, but all others older than 12 months should receive hepatitis A vaccine as recommended for children in the United States.7
In many countries, measles vaccine is not given in combination with mumps and rubella but is given as an individual component vaccine. Age of administration may be before the recommended age in the United States (12 months) because of concern about increased risk of exposure in those countries.
In the study of Verla-Tibet et al.,12 19.2% of children had no protective immunity despite documented immunization. Rates of protection were fairly similar when comparing China, Russia, and other countries. Viviano et al.15 found that only 62.5% of those with reported vaccinations had protective immunity to measles. Antibodies were positive for mumps in 56% and rubella in 85.7%. In the Schulte et al. study, only 56% of adoptees older than 12 months had documentation of MMR vaccine.21 Cilleruelo et al.16 noted that only 18.2% of adoptees had documentation of MMR, while the rate for monovalent measles vaccine was 51.3%. Protective immunity for measles was found in 79%, while the rates for mumps and rubella were 30% and 38%, respectively.
There have been reports of measles cases among international adoptees from China that have resulted in the recommendation that household and other close contacts of international adoptees have immunization against measles verified or updated, and that the adoptees themselves receive immunization soon after arrival.5,6 Children without documentation of mumps or rubella vaccination should receive immunization with two doses of MMR, regardless of documentation of measles vaccination.22 Those who have received a documented MMR vaccine can have antibodies to all three viruses measured by enzyme-linked immunoassay to determine if they have protective levels of antibody. If present, they need only one additional MMR.
Of the primary countries of origin for international adoptees, only South Korea recommends varicella vaccination at 12 to 15 months, as in the United States.10 Although immunization status could be verified with serology, it would be reasonable to vaccinate all children with two doses of varicella vaccine unless history or examination is clearly suggestive of past infection.23
Haemophilus Influenza Type B
Vaccination against Haemophilus influenzae type b (Hib) is recommended in Guatemala and Ethiopia but does not follow the standard recommendations of the United States.10 Guatemala recommends vaccination at 2, 4, and 6 months without a 12- to 15-month booster. In Ethiopia, vaccine is recommended at visits at 6, 10, and 14 weeks, without a booster after 12 months of age. Occasionally, children from China may have received one of more doses of Hib. For those children with documented vaccination, Hib antibody titers to polyribosylribitol phosphate could be measured to verify protective immunity. Otherwise, vaccination should be administered as would be age-appropriate.7
Pneumococcus (Streptococcus Pneumoniae)
Pneumococcal conjugate vaccine is not routinely recommended at this time in any of the primary countries of international adoptees. Children should be vaccinated according to the catch-up vaccination schedule, which varies by age at initial contact.7
Rotavirus vaccine is not routinely administered or recommended in the countries of origin of most international adoptees. Because most internationally adopted children are older than 15 weeks upon arrival in the United States, vaccination for rotavirus is unlikely to be possible given current rotavirus vaccine recommendations.7,23
All internationally adopted children are required to have a medical examination performed by a physician designated by the U.S. Department of State in their country of origin. Current laws for immigration to the United States require receipt of all vaccines recommended by the ACIP before obtaining an immigrant visa.24 However, internationally adopted children younger than 10 years are exempt from these requirements, as long as adopting parents sign a waiver indicating their intentions to comply with U.S. recommended immunizations within 30 days after the child arrives in the United States.25 It is essential that these children be seen soon after arrival to their new home to have their vaccine status evaluated.
The AAP provides three alternate approaches to immunization of internationally adopted children:8
accept written documentation of immunizations received by an adoptee as proof of immunization;
evaluate antibody titers to validate immunization status; and
disregard all records and completely reimmunize the child.
The latter approach has the potential to result in administering excessive vaccine doses, which can increase the risk of adverse events (particularly in the case of DTaP) or unnecessarily increase the cost of care for the child. Using the first approach is fraught with significant potential of overestimating the accuracy of these records, as pointed out by the studies discussed in this article. We prefer to take the second approach in most cases — ie, verifying immunity with serologic testing. Unfortunately, there are few studies that have evaluated the costeffectiveness of serologic screening versus simply re-immunizing the child.26 A quick reference guide to our approach to determining the vaccine needs of internationally adopted children is provided in the Sidebar (see page 523).
In children older than 6 months — perform serologic testing for specific IgG antibody to diphtheria and tetanus toxins. If both titers are above the protective level, complete the recommended age appropriate immunization schedule;7
if both titers are less than protective levels, fully reimmunize the child; if one titer is above and one is below protective levels, consider administering one dose of vaccine and remeasuring antibody titers in 1 month — a sharp rise in antibody titers would suggest prior immunization.IVP
In children older than 6 months — perform serologic testing for neutralizing antibody to poliovirus types 1, 2, and 3. If protective levels of antibody are present for all three serotypes, complete the recommended age appropriate immunization schedule.7
If titers to one or more polio serotypes are below the protective level, fully reimmunize the child.MMR
Reimmunize with two doses of MMR.7
Alternatively, in children older than 12 months, perform serologic testing for antibody to measles, mumps and rubella and reimmunize if any of the titers are below protective levels; if all are above protective levels, administer dose two at an appropriate age.7Hepatitis B
Perform serologic testing on all children to include surface antigens, surface antibodies, and core antibodies evaluations. If the child is older than 6 months and has protective titers of hepatitis B surface antibody, no further vaccines are needed. If there is no protective level of hepatitis B surface antibody, fully reimmunize. If there is evidence of active infection, immunization is unnecessary.Hib
Provide age-appropriate immunization;7
serologic testing for protective level of antibody is available if there is written documentation of Hib vaccine.Varicella
Provide age-appropriate immunization;7
serologic testing for protective level of antibody is available if there is a suggestion of previous illness.Hepatitis A
Perform serologic testing on all children to include IgM and IgG antibody; provide age-appropriate immunization if serologic testing is negative.7Pneumococcus
Provide age-appropriate immunization.7
- United States Department of State. Total Adoptions to the United States. Available at: adoption.state.gov/news/total_chart.html. Accessed July 17, 2010.
- Hostetter MK, Iverson S, Thomas W, McKenzie D, Dole K, Johnson DE. Medical evaluation of internationally adopted children. N Engl J Med. 1991;325(7):479–485. doi:10.1056/NEJM199108153250706 [CrossRef]
- Murray TS, Groth ME, Weitzman C, Cappello M. Epidemiology and management of infectious diseases in international adoptees. Clin Microbiol Rev. 2005;18(3):510–520. doi:10.1128/CMR.18.3.510-520.2005 [CrossRef]
- Fischer GE, Teshale EH, Miller C, et al. Hepatitis A among international adoptees and their contacts. Clin Infect Dis. 2008;47(6):812–814. doi:10.1086/591199 [CrossRef]
- Centers for Disease Control and Prevention (CDC). Measles outbreak among internationally adopted children arriving in the United States, February–March 2001. MMWR Morb Mortal Wkly Rep. 2002Dec13;51(49):1115–1116.
- CDC. Multistate investigation of measles among adoptees from China--April 9, 2004. MMWR Morb Mortal Wkly Rep. 2004;53(14):309–310.
- Advisory Committee on Immunization Practices (ACIP). Recommended Immunization Schedules for Persons Aged 0 to 18 Years. MMWR Morb Mortal Wkly Rep. 2010;58 (51&52):1433–1472.
- Pickering LK, Baker CJ, Long SS, McMillan JA, eds. Medical Evaluation of Internationally Adopted Children for Infectious Diseases. Redbook, Report of the Committee on Infectious Diseases. 28th ed. 2009:183.
- Kroger AT, Atkinson WL, Marcuse EK, Pickering LKACIP, CDC. General recommendations on immunization: Recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR Recomm Rep. 2006;55(RR-15):1–48.
- World Health Organization. WHO vaccine preventable diseases monitoring system. www.who.int/immunization_monitoring/en/globalsummary/scheduleselect.cfm. Accessed July 17, 2010.
- ACIP. Use of diphtheria toxoid-tetanus toxoidacellular pertussis vaccine as a five-dose series. Supplemental recommendations of ACIP. MMWR Recomm Rep. 2000;49(RR-13):1–8.
- Verla-Tebit E, Zhu X, Holsinger E, Mandalakas AM. Predictive value of immunization records and risk factors for immunization failure in internationally adopted children. Arch Pediatr Adolesc Med. 2009;163(5):473–479. doi:10.1001/archpediatrics.2009.26 [CrossRef]
- van Schaik R, Wolfs TF, Geelen SP. Improved general health of international adoptees, but immunization status still insufficient. Eur J Pediatr. 2009;168(9):1101–1106. doi:10.1007/s00431-008-0895-7 [CrossRef]
- Schulpen TW, van Seventer AH, Rumke HC, van Loon AM. Immunisation status of children adopted from China. Lancet. 2001;358(9299):2131–2132. doi:10.1016/S0140-6736(01)07188-4 [CrossRef]
- Viviano E, Cataldo F, Accomando S, Firenze A, Valenti RM, Romano N. Immunization status of internationally adopted children in Italy. Vaccine. 2006;24(19):4138–4143. doi:10.1016/j.vaccine.2006.02.029 [CrossRef]
- Cilleruelo MJ, de Ory F, Ruiz-Contreras J, et al. Internationally adopted children: What vaccines should they receive?Vaccine. 2008;26(46):5784–5790. doi:10.1016/j.vaccine.2008.08.029 [CrossRef]
- CDC. Updated recommendations of ACIP regarding routine poliovirus vaccination. MMWR Morb Mortal Wkly Rep. 2009;58(30):829–830.
- Mast EE, Margolis HS, Fiore AE, et al. ACIP. A comprehensive immunization strategy to eliminate transmission of hepatitis B virus infection in the United States: Recommendations of ACIP part 1: Immunization of infants, children, and adolescents. MMWR Recomm Rep. 2005;54(RR-16):1–31.
- Stadler LP, Mezoff AG, Staat MA. Hepatitis B virus screening for internationally adopted children. Pediatrics. 2008;122(6):1223–1228. doi:10.1542/peds.2007-2559 [CrossRef]
- CDCACIP. Updated recommendations from ACIP for use of hepatitis A vaccine in close contacts of newly arriving international adoptees. MMWR Morb Mortal Wkly Rep. 2009;58(36):1006–1007.
- Schulte JM, Maloney S, Aronson J, San Gabriel P, Zhou J, Saiman L. Evaluating acceptability and completeness of overseas immunization records of internationally adopted children. Pediatrics. 2002;109(2):E22. doi:10.1542/peds.109.2.e22 [CrossRef]
- Watson JC, Hadler SC, Dykewicz CA, Reef S, Phillips L. Measles, mumps, and rubella--vaccine use and strategies for elimination of measles, rubella, and congenital rubella syndrome and control of mumps: Recommendations of ACIP. MMWR Recomm Rep. 1998;47(RR-8):1–57.
- Cortese MM, Parashar UDCDC. Prevention of rotavirus gastroenteritis among infants and children: Recommendations of ACIP. MMWR Recomm Rep. 2009;58(RR-2):1–25.
- CDC. Vaccination Requirements for U.S. Immigration: Technical Instructions for Panel Physicians. www.cdc.gov/immigrantrefugeehealth/pdf/2009-ti-vaccination.pdf. Accessed July 17, 2010.
- Pickering LK, Baker CJ, Freed GL, et al. Infectious Diseases Society of America. Immunization programs for infants, children, adolescents, and adults: Clinical practice guidelines by the Infectious Diseases Society of America. Clin Infect Dis. 2009;49(6):817–940. doi:10.1086/605430 [CrossRef]
- Barnett ED. Immunizations and infectious disease screening for internationally adopted children. Pediatr Clin North Am. 2005;52(5):1287–1309. doi:10.1016/j.pcl.2005.06.004 [CrossRef]
Recommended Immunization Schedules by Country1
|United States||China||Russia||Guatemala||Ethiopia||South Korea|
|Hep A||12–23 x2||18||---||---||---||---|