BACKGROUND:
The majority of children in the US are privately insured. Little is known about the extent of vaccination coverage among insured US children.

OBJECTIVE:
To estimate the Diphtheria-tetanus-pertussis (DTP) vaccination coverage based on vaccinations administered in-plan.

METHOD:
We conducted a retrospective study of the Medstat MarketScan database, which include enrollees (children and adults) of approximately 100 self-insured health insurance plans of 45 large employers each year. We selected all children born between July 1, 1997 and June 30, 1998 who were continuously enrolled until the end of 1999. The DTP vaccination coverage among children aged 18 to 29 months was estimated based on in-plan administration of 3 or more doses of DTP vaccine (DTP3) and analyzed by characteristics of the families and their health insurance plans.

RESULT:
Overall DTP3 in-plan vaccination coverage was 47.3%. The coverage rates for children residing in metropolitan statistical areas (MSA) and non-MSAs were 52.7 and 31.1%, respectively; for children who enrolled in health maintenance organization, point of service, preferred provider organization and fee for service coverage rates were 79.3%, 77.3%, 32.3% and 18.9%, respectively; for children who enrolled in capitated insurance plans coverage was 75.1% vs non-capitated plans (34.3%). Of children with well-baby coverage in their plan, 77.2% were vaccinated, while 26.3% without that benefit were vaccinated.

CONCLUSION:
Among employer-sponsored self-insured health plans, vaccination coverage based on vaccinations administered in-plan was highest in those that were capitated and for those children in plans which had well-baby coverage. Knowledge of how vaccination coverage is related to families and their health plan characteristics may provide guidance for policy-makers to improve vaccination among children in the U.S.

LEARNING OBJECTIVES:
understand the in-plan vaccination coverage in employer-sponsored self-insured health plans.