[Impact of vaccination against Haemophilus influenzae on the incidence of invasive infections from Haemophilus influenzae type B in the Nord-Pas-de-Calais region].

BACKGROUND

In industrialized countries where immunization against Haemophilus influenzae b (Hib) is largely used, the incidence of invasive Hib infections has dramatically decreased. The aim of this study was to analyse the impact of immunization against Hib on the incidence of invasive Hib infections in the Nord-Pas-de-Calais area in France.

PATIENTS AND METHODS

This retrospective multicenter study enrolled 11 of the 18 hospitals in the Nord-Pas-de-Calais area, comparing two periods: 1991-1993 (before immunization), and 1994-1996 (during immunization). All children less than 60 months of age and having an invasive Hib infection were included. The Pasteur-Mérieux Company was asked to provide the number of vaccines sold in the Nord-Pas-de-Calais area during the study period.

RESULTS

The number of vaccines sold in 1992 was 56,208; this reached 189,173 in 1996, corresponding to an immunization ratio higher than 90%. One hundred and two children representing 155 invasive Hib infections were studied. The annual incidence was 42 during the first period (meningitis: 18.6; septicemia: 14.6; epiglottitis: 5.6), and nine (meningitis: 5; septicemia: 2.6; epiglottitis: 0.3) during the second period, that is a 78% decrease.

CONCLUSION

These results confirm previous data in the literature by demonstrating that immunization in the Nord-Pas-de-Calais area has dramatically decreased the incidence of invasive Hib infections.