Haemophilus influenzae type b disease: impact and effectiveness of diphtheria-tetanus toxoids-acellular pertussis (-inactivated poliovirus)/H. influenzae type b combination vaccines.
BACKGROUND
Since 1996 in Germany primary infant immunization against Haemophilus influenzae has been most commonly given in the form of diphtheria-tetanus toxoids-acellular pertussis/H. influenzae type b (DTaP/Hib) or diphtheria-tetanus toxoids-acellular pertussis (-inactivated poliovirus)/H. influenzae type b (DTaP-IPV/Hib) combination vaccines. These combination vaccines elicit lower anti-Hib antibody concentrations than the equivalent Hib conjugate administered as a separate injection, but the clinical relevance of this phenomenon is unknown.


RESULTS
To assess the impact of DTaP/Hib combination vaccines on the incidence of invasive Hib disease in Germany, two independent surveillance systems, one hospital- and one laboratory-based, were used during 1998 and 1999 for detection of cases. Vaccination histories of all cases detected were obtained by telephone contact with parents or health care providers. During the 2-year study period invasive H. influenzae disease in the <5-year age group continued to fall, with a mean annual incidence of 1.01/100 000 children. National vaccination coverage rates revealed that only 70% of children given DTaP/Hib or DTaP-IPV/Hib received the recommended three doses in their first year of life, but the overall effectiveness of these vaccines was high at 97.5% (95% confidence interval, 96.3 to 98.4) for those who had received at least one dose. In subjects who received the full 3-dose schedule, effectiveness was 98.8% (95% confidence interval, 98.2 to 99.3).


CONCLUSIONS
Although it is well-documented that DTaP/Hib vaccines elicit lower anti-Hib titers than separate vaccines, such combinations are effective in reducing the incidence of invasive H. influenzae type b disease.
Schmitt
H J
HJ
Pediatric Infectious Diseases Service, Department of Pediatrics at the Center for Preventive Pediatrics, Johannes Gutenberg University, Mainz, Germany. Schmittj@kinder.klinik.uni-mainz.de
von Kries
R
R
Hassenpflug
B
B
Hermann
M
M
Siedler
A
A
Niessing
W
W
Clemens
R
R
Weil
J
J
D000907:Antibodies, Bacterial / Q000097:blood; D002675:Child, Preschool; D022681:Diphtheria-Tetanus-acellular Pertussis Vaccines / Q000008:administration & dosage* / Q000276:immunology; D005858:Germany / Q000453:epidemiology; D006192:Haemophilus Infections / Q000453:epidemiology / Q000517:prevention & control*; D018073:Haemophilus Vaccines / Q000008:administration & dosage* / Q000276:immunology; D019741:Haemophilus influenzae type b / Q000145:classification / Q000276:immunology* / Q000302:isolation & purification; D006801:Humans; D007115:Immunization Schedule; D015994:Incidence; D007223:Infant; D011054:Poliovirus Vaccine, Inactivated / Q000008:administration & dosage* / Q000276:immunology; D018571:Sentinel Surveillance; D014611:Vaccination; D017778:Vaccines, Combined / Q000008:administration & dosage / Q000276:immunology
D000907:Antibodies, Bacterial; D022681:Diphtheria-Tetanus-acellular Pertussis Vaccines; D018073:Haemophilus Vaccines; D011054:Poliovirus Vaccine, Inactivated; D017778:Vaccines, Combined