Modelling long-term vaccination strategies with MenAfriVac® in the African meningitis belt
Clinical Infectious Diseases
Oxford University Press
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Karachaliou, A., Conlan, A., Preziosi, M., & Trotter, C. (2015). Modelling long-term vaccination strategies with MenAfriVac® in the African meningitis belt. Clinical Infectious Diseases, 61 S594-S600. https://doi.org/10.1093/cid/civ508
A mathematical model of Neisseria meningitidis A transmission and disease was used to evaluate long-term strategies for optimal future use of MenAfriVac® to sustain population protection. Using a combination strategy of introduction into routine immunization programmes at 9 months of age, 5 years after the initial mass campaigns, and a one-off catch-up targeting unvaccinated 1-4 year olds, appeared to be the most attractive strategy. Background The introduction of MenAfriVac® in campaigns targeting 1-29 year olds across the African meningitis belt has successfully reduced meningitis incidence and carriage due to Neisseria meningitidis group A (NmA). It is important to consider how best to sustain population protection in the long-term. Methods We created a mathematical model of NmA transmission and disease to investigate the potential impact of a range of immunisation 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 pre-vaccine 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 immunisation, strong resurgences in disease incidence were predicted after approximately 15 years (assuming 10 years average vaccine protection). Routine immunisation at 9 months of age resulted in lower average annual incidence than regular mass campaigns of 1-4 year olds, provided coverage was above ~60%. The strategy with the lowest overall average annual incidence and longest time to resurgence was achieved using a combination strategy of introduction into EPI at 9 months, 5 years after the initial mass campaigns, with a catch-up targeting unvaccinated 1-4 year olds. Conclusions These results can be used to inform policy recommendations for long term vaccination strategies with MenAfriVac®.
Meningitis, Vaccine, Africa, Mathematical modelling
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.
Program for Appropriate Technology in Health (PATH) (GAT0779-06290-COL)
Wellcome Trust (100891/Z/13/Z)
External DOI: https://doi.org/10.1093/cid/civ508
This record's URL: https://www.repository.cam.ac.uk/handle/1810/248770
Creative Commons Attribution 4.0
Licence URL: http://creativecommons.org/licenses/by/4.0/