Modeling strain replacement in the African meningitis belt
The introduction of MenAfriVac in mass vaccination campaigns across the African meningitis belt has successfully reduced meningitis incidence and carriage of Neisseria meningitidis group A (NmA). However, other meningococcal serogroups continue to circulate and cause disease in the region, and it is unclear how these groups might behave in the absence of NmA transmission. To explore this scenario, we created a transmission model of two strains of Nm: NmA and a strain unaffected by the vaccine. Our results suggest that there may be some replacement in carriage following widespread implementation of MenAfriVac. However, the results vary widely according to changes in model structure and assumptions. In particular, the magnitude of replacement depends principally on the specificity of immunity conferred by nasopharyngeal carriage, for which we have little data at present. We therefore recommend caution in interpreting model-based predictions in the context of the epidemiology of disease in the meningitis belt. These findings will be relevant in future as assumptions about replacement will critically impact predictions about the effectiveness of a pentavalent vaccine, scheduled to be licensed in 2023.
About the speaker
Laura completed her undergraduate degree at Princeton University in Ecology and Evolutionary Biology. She joined the Disease Dynamics Unit at Cambridge in 2015 as a master’s student with Caroline Trotter working on the epidemiology of bacterial meningitis in the African meningitis belt . Laure completed her PhD in the same area in 2019. She is now working on the epidemiology of poliovirus transmission as a Research Associate in the Vaccine Epidemiology Research Group at Imperial College.