BACKGROUND:
In 1991, the ACIP recommended universal immunization against Hepatitis B. In 1994, the NIS immunization rate for 3 doses of Hepatitis B was 37%. By 2002, it was 89.9%.
Biologics Surveillance System (BSS) data contain manufacturer-reported annual net sales/distribution of vaccines in the US. BSS data are used to estimate vaccine coverage levels and manufacturer market share.

OBJECTIVE:
To compare BSS net distribution of pediatric Hepatitis B vaccine from 1991-2002 with NIS coverage rates and US Census birth data; to estimate the theoretical number of birth cohorts the net 1991-2002 distribution of pediatric Hepatitis B vaccine could have immunized.

METHOD:
1991-2002 BSS data on net sales/distribution of pediatric Hepatitis B vaccine were evaluated against US Census birth cohort data and NIS coverage rates to derive an estimate of the number of children who could have received a 3-dose series.

RESULT:
Census data indicate 47,805,902 were born between 1991 and 2002. BSS data indicate 218,554,222 net doses of pediatric Hepatitis B were distributed during this period - equivalent to 4.6 doses per birth. Adjusted to 3 doses per birth, the amount was sufficient to fully immunize 72,851,407 children, or 18 cohorts (e.g. all births between 1985 and 2002).

CONCLUSION:
Net pediatric Hepatitis B vaccine distribution between 1991 and 2002 was sufficient to fully immunize all US births between 1985 and 2002, yet NIS data indicate Hepatitis B coverage has ranged from 37% in 1994 to 90% in 2002. Possible factors for the excess pediatric Hepatitis B distribution include catch-up campaigns, over-immunization, higher than expected wastage, and use of the vaccine in adults.

LEARNING OBJECTIVES:
The learner should be able to state when universal Hepatitis B recommendations began, how many net doses of pediatric Hepatitis B vaccine were distributed between 1991 and 2002, how many fully immunized birth cohorts this represents and reasons for the disparity.