Bacterial meningitis is a potentially severe infection of the meninges, the thin lining of the brain and spinal cord. The common symptoms are sudden onset of headache, high fever, stiff neck and sensitivity to light. In 2021, WHO launched a global road map to "defeat meningitis by 2030", after its approval by the World Health Assembly at its Seventy-third session in November 2020. (1) The road map addresses the 4 main causes of acute bacterial meningitis: Streptococcus pneumoniae (Spn), Haemophilus influenzae, Neisseria meningitidis (Nm) and Streptococcus agalactiae (commonly referred to as "group B streptococcus"). The 3 visionary goals to be achieved by 2030 are: (1) elimination of meningitis epidemics; (2) reductions by 50% in the number of cases and by 70% in the number of deaths from vaccine-preventable meningitis; and (3) a reduction in disability and an improvement in the quality of life after meningitis of any cause.
Of the bacterial meningitis pathogens, the meningococcus (Nm) is of particular concern because of its potential to cause large epidemics. Of the 12 Nm subtypes or serogroups identified, 6 (A, B, C, W, X and Y) are recognized as the main causes of disease and epidemics. Although meningococcal meningitis occurs worldwide, large, recurring epidemics mainly affect an extensive region of sub-Saharan Africa known as the "meningitis belt", which comprises 26 countries, stretching from Senegal to Ethiopia. The pneumococcus (Spn), which has over 90 capsular serotypes, has also been associated with several meningitis outbreaks and causes an increasing proportion of meningitis cases in the belt. Most meningitis cases and outbreaks in the African meningitis belt occur during the epidemic season, which can extend from November to June, depending on the region and year.
Introduction of meningococcal A conjugate vaccine
Before introduction of a meningococcal A conjugate vaccine (MenACV) (2) in mass preventive campaigns and routine immunization programmes, Nm serogroup A was responsible for most meningitis epidemics in the meningitis belt. (3)
The recommended MenACV introduction strategy has 2 axes. (4) Mass vaccination of a broad age group (1-29 years) provides herd protection by reducing bacterial carriage and transmission and thus dramatically reduces the incidence, with immediate benefits for public health. Introduction into routine childhood immunization, recommended at the latest 5 years after completion of mass campaigns, provides continued protection of new birth cohorts and thus maintains the population protection.
Between 2010 and 2019, 24 of the 26 countries in the meningitis belt conducted mass preventive campaigns, either nationwide or in high-risk areas. After evaluation of their risk, the 2 remaining countries, Rwanda and the United Republic of Tanzania, decided to give priority to strengthening their meningitis surveillance systems before considering introduction of meningococcal vaccines.
As of December 2020, 11 countries had introduced MenACV into their national childhood immunization programmes. Despite the challenges related to COVID-19, Guinea and Togo proceeded with its introduction, in March and December 2021, respectively.
The introduction in Guinea, initially planned for 2020, took place in March 2021, when MenACV was introduced into the national immunization programme, targeting children...