A conjugate vaccine for Neisseria meningitidis serogroup A (MenAfriVac) was introduced through mass campaigns in people aged 1–29 years in the African meningitis belt and is now being added to national infant immunisation programmes. 1 Following the mass campaigns in 2010–17, incidence of N meningitidis serogroup A meningitis has declined from a hyperendemic pattern with regular epidemics to a few sporadic cases. 2 The hope is that control of the disease will be long lasting. The mechanism for such control would be the initial interruption of circulation of N meningitidis serogroup A in the population through the effect of the vaccine against asymptomatic nasopharyngeal infection, followed by sustained direct protection against disease, including in new birth cohorts. The duration of persistence of antibodies is a major variable in this scheme.