Background: Routine use of hepatitis B vaccine for low-risk newborns was suspended on July 7, 1999, because of concern about the potential risk of thimerosal, a mercury-containing vaccine preservative. Reinstatement of the birth dose was recommended when a thimerosal-free vaccine became available. Objective: To explore changes in hepatitis B vaccination practices for newborns related to the revised recommendations for low-risk infants (in this study, the terms newborn and infant are used interchangeably). Design: A telephone survey of a random sample of 1000 US hospitals. Participants: Nurse managers, nursery directors, and staff nurses of the newborn nurseries. Main Outcome Measures: Nursery vaccination practices before and after July 7, 1999, and the availability and use of thimerosal-free vaccine. Results: Interviews were conducted with 773 (87%) of 886 eligible hospitals. Before July 7,1999, 78% of the hospitals reported vaccination practices that were consistent with recommendations at that time, although only 47% vaccinated all low-risk infants at birth. After July 7, 1999, almost all hospitals discontinued vaccination of low-risk infants, in accordance with the recommendation change; however, there was a 6-fold increase in the number of hospitals that were not vaccinating all high-risk infants. After the introduction of thimerosal-free vaccine, only 39% of the hospitals reported vaccinating all low-risk infants. Conclusions: Most hospital nurseries altered their newborn hepatitis B vaccination practices consistent with changes in national recommendations. However, unintended consequences included the failure of some hospitals to continue vaccinating all high-risk infants and the delay in reintroducing vaccination for low-risk newborns after the introduction of a thimerosal-free vaccine. Assessments of the appropriateness of this country's response to the threat of thimerosal in vaccines should consider these findings.
