immunity National Center for Biotechnology Information NCBI NLM MEDLINE review clinical trials as topic humans pubmed abstract nih national institutes of health national library of medicine treatment outcome Forecasting meningitis meningococcal / prevention & control immunization schedule developing countries diederik van de beek bacterial / prevention & control* bacterial / epidemiology global health haemophilus influenzae pneumococcal infections / prevention & control cost of illness pmid:23141619 doi:10.1016/s0140-6736(12)61187-8 peter b mcintyre katherine l o'brien bacterial vaccines* developed countries gram-negative bacterial infections / prevention & control* gram-positive bacterial infections / prevention & control* haemophilus infections / prevention & control herd neisseria meningitidis streptococcus pneumoniae