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Modeling Long-term Vaccination Strategies With MenAfriVac in the African Meningitis Belt.


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Authors

Karachaliou, Andromachi 
Conlan, Andrew JK 
Preziosi, Marie-Pierre 
Trotter, Caroline L 

Abstract

BACKGROUND: The introduction of MenAfriVac in campaigns targeting people aged 1-29 years across the African meningitis belt has successfully reduced meningitis incidence and carriage due to Neisseria meningitidis group A (MenA). It is important to consider how best to sustain population protection in the long term. METHODS: We created a mathematical model of MenA transmission and disease to investigate the potential impact of a range of immunization strategies. The model is age structured; includes classes of susceptible, carrier, ill, and immune people (who may be vaccinated or unvaccinated); and incorporates seasonal transmission and a stochastic forcing term that models between year variation in rates of transmission. Model parameters were primarily derived from African sources. The model can describe the typical annual incidence of meningitis in the prevaccine era, with irregular epidemics of varying size. Parameter and structural uncertainty were explored in sensitivity analyses. RESULTS: Following MenAfriVac introduction at high uptake, the model predicts excellent short-term disease control. With no subsequent immunization, strong resurgences in disease incidence were predicted after approximately 15 years (assuming 10 years' average vaccine protection). Routine immunization at 9 months of age resulted in lower average annual incidence than regular mass campaigns of 1- to 4-year-olds, provided coverage was above approximately 60%. The strategy with the lowest overall average annual incidence and longest time to resurgence was achieved using a combination strategy of introduction into the Expanded Programme on Immunization at 9 months, 5 years after the initial mass campaigns, with a catch-up targeting unvaccinated 1- to 4-year-olds. CONCLUSIONS: These results can be used to inform policy recommendations for long-term vaccination strategies with MenAfriVac.

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Keywords

Africa, mathematical modeling, meningitis, vaccine, Adolescent, Adult, Africa, Age Factors, Aged, Aged, 80 and over, Child, Child, Preschool, Disease Transmission, Infectious, Female, Humans, Infant, Infant, Newborn, Male, Meningitis, Meningococcal, Meningococcal Vaccines, Middle Aged, Models, Theoretical, Seasons, Vaccination, Young Adult

Journal Title

Clin Infect Dis

Conference Name

Journal ISSN

1058-4838
1537-6591

Volume Title

61

Publisher

Oxford University Press (OUP)
Sponsorship
Program for Appropriate Technology in Health (PATH) (GAT0779-06290-COL)
Wellcome Trust (100891/Z/13/Z)
This work was funded by a grant from the Meningitis Vaccine Project (via PATH). Caroline Trotter received salary support from the MenAfriCar project, funded by grants from the Wellcome Trust and the Bill and Melinda Gates Foundation. This article appeared as part of the supplement ‘The development, licensure, introduction and impact of a new Group A meningococcal conjugate vaccine for Africa’ sponsored by the Bill & Melinda Gates Foundation.