Objectives: To measure the predictive value of immunization records for protective immunity and identify risk factors for immunization failure.
Design: Prospective cross-sectional study, 2001-2006.
Setting: International Adoption Clinic, Rainbow Babies and Children's Hospital, Cleveland, Ohio.
Participants: A total of 465 international adoptees presenting within 180 days of arrival. Main Exposure Immunization records of vaccines given.
Outcome measures: Protective immunity to polio, hepatitis B, tetanus, diphtheria, and measles.
Results: Vaccination records were available for 397 (85.4%) adoptees (mean age, 19.4 months; 65.2% girls). Most children came from Russia (41.7%), China (20.9%), and Guatemala (15.7%). Acute or chronic malnutrition was present in 5.5% and 15.4% of adoptees, respectively. Preadoptive settings were institutional (52%), community-based (14%), or both (34%). Of adoptees with 3 or more tetanus (n = 203) or 3 or more diphtheria (n = 205) vaccinations, 87.2% and 94.6% had protective immunity, respectively. Of adoptees with 3 or more polio vaccinations (n = 216), protective immunity was present in 58.3%, 82.4%, and 51.9% for polio types 1, 2, and 3, respectively. Of adoptees with 2 or more hepatitis B vaccinations (n = 170), 94.1% had protective immunity. A total of 80.8% of adoptees with measles vaccination (n = 99) had protective immunity. Children from China were less likely to have protective immunity than children from Russia (odds ratio, 0.34; 95% confidence interval, 0.17-0.66). Nutritional status had no predictive effect.
Conclusions: The predictive value of immunization records in international adoptees is limited and varies between birth countries. Immunization records should not be accepted as evidence of protective immunity. Parents should be well informed and supported to choose between revaccination or vaccination, based on serologic testing.