Four and one-half-year follow-up of the effectiveness of diphtheria-tetanus toxoids-acellular pertussis/Haemophilus influenzae type b and diphtheria-tetanus toxoids-acellular pertussis-inactivated poliovirus/H. influenzae type b combination vaccines in Germany.
BACKGROUND
Recently an increase in the number of invasive Haemophilus influenzae type b (Hib) cases was observed in the United Kingdom, which coincided with a temporary change from diphtheria-tetanus toxoids-wild-type pertussis to diphtheria-tetanus toxoids-acellular pertussis (DTaP) Hib vaccines. A study in Germany based on approximately 2 years of follow-up, estimated vaccine effectiveness (VE) of DTaP/Hib and DTaP-inactivated poliovirus/Hib combination vaccines against invasive Hib disease to be high.


OBJECTIVE
To assess VE of DTaP-containing Hib vaccines against Hib in Germany with the use of extended follow-up of case surveillance and vaccine uptake.


METHODS
Cases with confirmed systemic Hib infections in children born between June 1, 1996 and December 31, 1998 were ascertained by a nationwide active surveillance system from January 1998 through June 2002. A representative subcohort of 667 children born in the same time frame was randomly sampled in a nationwide vaccine coverage survey. VE was determined with a case-cohort approach of Cox regression with time-dependent covariates.


RESULTS
Thirty-six cases of Hib disease were reported. Of these, 10 were vaccinated with DTaP-containing Hib vaccines only and 20 were not vaccinated. Of the 10 vaccinated cases, 4 had received an incomplete primary series (1-2 doses), and 6 had received the full primary series (3 doses), 3 of whom also received the booster dose. VE of combination vaccines against invasive Hib infection was 89.6% [95% confidence interval (CI), 67.0-96.7] for an incomplete primary series, 96.7% (95% CI 87.7-99.1) for a full primary series and 98.5% (95% CI 94.5-99.6) for a booster dose (irrespective of priming).


CONCLUSIONS
Hib combination vaccines containing acellular pertussis antigens continue to be highly effective in Germany.
Kalies
Helen
H
Institute for Social Pediatrics and Adolescent Medicine, Ludwig-Maxilimilians-University, Heiglhofstrasse 63, 81377 Munich, Germany. helen.kalies@lrz.uni-muenchen.de
Verstraeten
Thomas
T
Grote
Veit
V
Meyer
Nicole
N
Siedler
Anette
A
Schmitt
Heinz-Josef
HJ
Breuer
Thomas
T
Moulton
Lawrence H
LH
von Kries
Rüdiger
R
D016022:Case-Control Studies; D002675:Child, Preschool; D015331:Cohort Studies; D022681:Diphtheria-Tetanus-acellular Pertussis Vaccines / Q000276:immunology*; D005858:Germany / Q000453:epidemiology; D006192:Haemophilus Infections / Q000453:epidemiology / Q000517:prevention & control*; D018073:Haemophilus Vaccines / Q000276:immunology*; D019741:Haemophilus influenzae type b / Q000276:immunology*; D006801:Humans; D007223:Infant; D023321:Poliovirus Vaccines / Q000276:immunology*; D012189:Retrospective Studies; D017778:Vaccines, Combined / Q000276:immunology
D022681:Diphtheria-Tetanus-acellular Pertussis Vaccines; D018073:Haemophilus Vaccines; D023321:Poliovirus Vaccines; D017778:Vaccines, Combined