Impact of routine vaccination with a conjugate Haemophilus influenzae type b vaccine.

Based on a unique nationwide registration of vaccinated children, we studied the impact of routine Hib vaccination with special emphasis on vaccine uptake and adherence, vaccine effectiveness with respect to Hib meningitis, and indirect effects with respect to Hib meningitis among the unvaccinated children. Uptake and adherence was generally satisfactory. We estimated >97% effectiveness for all three doses of vaccine and observed herd-immunity in unvaccinated children comparable to a vaccine effectiveness of 94% 3.5 years into the programme. In conclusion, nationwide routine Hib vaccination is highly effective in protecting against Hib meningitis, and rapid achievement of herd immunity is possible with catch-up vaccination of older children.