The impact of DTaP-IPV-HB vaccine on use of health services for young infants. 
In 2003, a pentavalent vaccine (diphtheria, tetanus and acellular pertussis, injectable polio and hepatitis B) was introduced into the childhood vaccination schedule.  A premarketing study showed a higher incidence of fever than with the vaccines administered separately.  Because fevers in young infants prompt medical evaluations, this study examines the impact of this vaccine (DTaP-IPV-HB) on subsequent use of health services.  We compared use of health services among 6- to 10-week-old infants receiving DTaP-IPV-HB (n = 1776) with a historical control receiving the prior schedule (n = 2162) at an inner-city practice network.  Data sources included a hospital immunization registry and medical records.  Outcome measures were visits to the emergency department and ambulatory practices, fever, tests, antibiotics and hospitalizations.  Outcomes were stratified by age (<8, 8-10 weeks) and days since vaccination (3, 7).  Infants vaccinated with DTaP-IPV-HB were more likely to visit the ED (1.2% versus 0.6%, P = 0.03) and receive tests (47.6% versus 8.3%, P = 0.03) within 3 days of vaccination compared with the controls.  Multivariate analysis showed infants vaccinated with DTaP-IPV-HB had a 7-fold increased risk of receiving a full sepsis workup and a 3-fold increased risk of receiving antibiotics within 7 days of vaccination.  Medical evaluations decreased over time after implementation of the DTaP-IPV-HB vaccine.  Concurrently, the rate of vaccination for infants <8 weeks markedly dropped.  The DTaP-IPV-HB vaccine was associated with increased use of health services in the emergency department, but these associations lessened over time.  These findings reveal a conflict between the obligation of timely and efficient vaccination with the medical management of febrile young infants.