Conjugate vaccines dramatically reshaped the epidemiology of bacterial meningitis in a well-defined child population.

Abstract

We explored the impact of vaccination on bacterial meningitis in a well-defined population of children on the island of Crete, Greece, over a 27-y period. This was a retrospective observational study of all mandatory notifications of bacterial meningitis in patients aged 1mo-14y from 1991 to 2017. There were 245 patients with proven (n=227) or suspected (n=18) bacterial meningitis, and eight deaths were recorded, giving a case fatality rate of 3.3%. The mean annual incidence rate (IR) per 100000 children was 4.9 for Neisseria meningitidis, 2.2 for Streptococcus pneumoniae and 0.4 for Haemophilus influenzae type b (Hib). Cases of meningitis C dropped significantly after the conjugate meningitis C vaccine was licensed for routine vaccination in Greece in 2000 (IR of 1.5 vs 0.3, P<0.028) while the Streptococcus pneumoniae cases showed a threefold decrease after the PCV13 vaccine was licensed in Greece in 2009 (IR 2.7 vs 1.0, P<0.03). Vaccination had already eliminated Hib in Greece in the 1990s. Bacterial meningitis cases decreased in children following the introduction of the meningitis C and PCV13 vaccines in Greece. Hib had already disappeared and significant reductions in meningitis C and Streptococcus pneumoniae were observed.