Comparison of cost-effectiveness of preventive and reactive mass immunization campaigns against meningococcal meningitis in West Africa: a theoretical modeling analysis.

For epidemic meningitis control in sub-Saharan Africa, the World Health Organization recommends a strategy of emergency vaccination with meningococcal A + C polysaccharide vaccine when epidemic thresholds are exceeded. An alternative strategy for areas without effective surveillance systems is mass preventive campaigns before outbreaks occur. A model was formulated to simulate epidemics and to compare the cost-effectiveness of these two strategies for the district of Matam, Senegal, where an actual preventive campaign was performed during 1997. The preventive strategy prevented 59% of the cases compared to 49% for the emergency strategy. The cost per case prevented was US$59 for the preventive strategy and US$133 for the reactive strategy, and the preventive strategy saved US$0.20 per habitant. Preventive meningococcal vaccination through mass campaigns prevented more outcomes at a lower cost, provided that the occurrence of an epidemic could be predicted within 3 years and that the vaccination coverage rates for the preventive and standard strategies were > 70% and < 94%, respectively. Sub-Saharan African countries without effective surveillance systems should consider mass preventive campaigns while awaiting an affordable conjugate vaccine.