Undervaccination with hepatitis B vaccine - Missed opportunities or choice?

Backrgounds: An estimated 1 million to 1.25 million people in the United St ates are chronically infected with hepatitis B virus (HBV) and are at subst antially increased risk of developing chronic liver disease, including cirr hosis and primary hepatocellular carcinoma, Immunization with hepatitis B v accine (HepB) is the most effective means of preventing HBV infection and i ts consequences. Methods: To identify and describe children who had not completed the three- dose HepB series, rye analyzed data from the 1999 National Immunization Sur vey (NIS). Among the 2648 children aged 19 to 35 months who did not complet e the HepB ser ies, eve examined the relationship between the number of dos es of HepB received and the number of vaccination visits made, receipt of t he birth dose of HepB, age at the time of first vaccination visit (excludin g that for the birth dose of HepB), and completion of the 4:3:1:3 series (f our doses of diphtheria and tetanus toxoids and pertussis vaccine, three do ses of poliovirus vaccine, one dose of measles-containing vaccine, and thre e doses of Haemophilus influensae type b vaccine [Hib]). Results: Overall, 11.8% of the children who were included in the 1999 NIS d id not complete the HepB series. Among these series-incomplete children, mo st (79.8%; 95% CI, 77.4%-82.2%) did not receive the birth dose of HepB, and most (80.2%; 95% CI, 77.6%-82.8%) had three or more vaccination visits. Mo st of the series-incomplete children (87.3%; 95% CI, 85.1%-89.5%) who had t hree or more vaccination visits received one or two doses of HepB. Among se ries-incomplete children with at least three vaccination visits, those who did not receive any HepB were more likely to have completed the 4:3:1:3 ser ies (67.1%; 95% CI, 58.8%-75.4%) than those who received at least one dose of HepB (52.7%; 95% CI, 49.0%-56.4%). Conclusion: Children who did not complete the HepB series fell into three d istinct groups: children who made at least three vaccination visits but did not begin the HepB series (n=326); children who made three or more vaccina tion visits and received one or two doses of HepB (n=1835); and children wh o made fewer than three vaccination visits (n= 487). Different intervention strategies are needed to have an impact on each of t hese groups. including understanding why parents and providers may not be r eceptive to HepB, decreasing missed opportunities to administer HepB, and i mplementing tracking systems such as registries to identify and contact chi ldren who are due or overdue for vaccinations.