Vaccine efficacy against Haemophilus influenzae serotype b (Hib) has not declined over time or with the combination hexavalent diphtheria, tetanus, and acellular pertussis-hepatitis B virus-inactivated polio virus/Hib vaccine (DTPa-HBV-IPV/Hib), according to a study published in The Lancet: Infectious Diseases.

Susana Monge, PhD, of the Centre for Infectious Disease Control at the National Institute for Public Health and the Environment in Bilthoven, Netherlands, and associates conducted a case-control analysis to determine the efficacy of the hexavalent vaccine and to understand its correlation with increased infection rates among children younger than 5 years.

A total of 159 pediatric patients <5 years of age infected with Hib were included in the study and matched with 1590 control participants with a median age of 1.5 years. Patients were administered either the hexavalent vaccine or a pentavalent vaccine that did not include hepatitis B virus compounds. Vaccines were administered to 91 (57%) patients in the case group and 1408 (89%) patients in the control group.

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The investigators reported no significant differences between the various vaccines administered. Total vaccine efficacy was 92.8%. Effectiveness of the pentavalent vaccine was 91.8% (and other control vaccines) compared with 94.0% for the hexavalent vaccine (odds ratio, 0.72).  

Results suggested that vaccine efficacy was higher in children between the ages of 1 and 2 years at disease onset (97.1%-99.0%) and lower in children between the ages of 3 and 4 at disease onset (60.7%-82.3%).

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“Our results support the current vaccination program, since Hib vaccine effectiveness has not decreased over time or by the introduction of the hexavalent DTPa-HBV-IPV/Hib vaccine,” the authors reported. “Vaccine effectiveness was high but waned with age. Alternative explanations for the increase of Hib disease therefore need to be assessed.”


Monge S, Hahné SJM, de Melker HE, Sanders EAM, van der Ende A, Knol MJ. Effectiveness of the DTPa-HBV-IPV/Hib vaccine against invasive Haemophilus influenzae type b disease in the Netherlands (2003-16): a case-control study [published online May 8, 2018]. Lancet. doi: 10.1016/S1473-3009(18)30166-X