Primary Immunization Series Coverage of Children With Sickle Cell Disease

Children with sickle cell disease are at increased risk of serious infections, many of which can be prevented by receipt of recommended immunizations. Study objectives were to (1) assess the primary immunization series coverage among children with sickle cell disease and (2) compare the coverage with that of those without sickle cell disease.

The Michigan Care Improvement Registry was used to obtain primary immunization series doses and sickle cell disease status for all eligible children in Michigan born in 2001-2016 (analysis was conducted in 2019). Completion of series and each individual vaccine were assessed for every child at ages 19 and 35 months. Proportions were stratified by sickle cell disease status and compared using chi-square tests. Logistic regression was used to model the odds of completing the series at each age, as predicted by sickle cell disease status and adjusting for the presence of Medicaid identification number.

The proportion of children who completed the immunization series was higher for those with sickle cell disease than for those without sickle cell disease at 19 months (58.5% vs 48.0%) and 35 months (74.7% vs 59.6%) (both p<0.0001). The odds of completing the series were 1.4 times higher at 19 months (95% CI=1.2, 1.6) and 1.7 times higher at 35 months (95% CI=1.5, 2.0) for children with sickle cell disease than for those without, adjusting for the presence of Medicaid identification number.

Although children with sickle cell disease had higher immunization rates than those without sickle cell disease, >40% of children with sickle cell disease did not receive all recommended immunizations by age 19 months. Immunization information systems should be utilized to improve routine immunization coverage of children with sickle cell disease.