Rollout of the meningococcal A conjugate vaccine in the African meningitis belt countries from 2010 to 2023: progress, challenges, and future directions

¹World Health Organization's African Region, Universal Health Coverage, Brazzaville, Republic of Congo, ²World health Organization Headquarters, the Immunization, Vaccines and Biologicals, Geneva, Switzerland, ³World health Organization, African Region's Emergency Preparedness and Response, Brazzaville, Republic of Congo, ⁴World Health Organization, Régional Office Africa, Brazzaville, Congo, ⁵World health Organization, Eastern Mediterranean Region, Nasr City, Cairo

^&Corresponding author
André Arsène Bita Fouda, World Health Organization's African Region, Universal Health Coverage, Brazzaville, Republic of Congo

Introduction    

Meningococcal meningitis is a major global public health problem including in the 26 countries that have the highest rates of the disease in the African meningitis belt, stretching from Senegal in the west to Ethiopia in the east [1-4]. Acute bacterial meningitis is one of the deadliest and disabling forms of the disease. One/six people die from it; death can occur in <24 hours. One in five people who survive live with long-term disability. It can cause large and devastating epidemics [1,5,6]. The infection can be caused by bacteria such as Neisseria meningitidis (N. meningitidis), Streptococcus pneumoniae (S. pneumoniae), Haemophilus influenzae (Hi), and Streptococcus agalactiae or group B streptococcus (GBS)), viruses, fungi, and parasites [1,7]. Before 2010, Neisseria meningitidis serogroup A (N. meningitidis A) was the predominant cause of meningitis epidemics, accounting for almost 85% [3,8].

The largest meningococcal meningitis epidemic was reported in 1996 and 1997, where more than 25,000 people died and more than 250,000 were affected. Following this devastating epidemic, African leaders called for the development of an affordable vaccine that would eliminate N. meningitidis A epidemics in Africa [9-11]. An affordable monovalent Meningococcal serogroup A polysaccharide-tetanus toxoid conjugate vaccine called MenACV was developed and prequalified in 2009 by WHO. MenACV has been introduced in African meningitis belt countries since 2010 [12,13]. Only the health districts that are at the highest risk were selected to introduce MenACV. The selection was made through the risk assessment using the district prioritization tool developed by World Health Organization (WHO) [14].

MenACV can provide herd and individual protection when a health district has reached at least 90% of administrative coverage or 70% of immunization coverage during a mass vaccination campaign. Between 2010 and 2018, 22 out of 26 countries of the African meningitis belt have introduced MenACV with over 300 million people vaccinated aged 1 to 29 years through preventive mass vaccination campaigns and routine vaccination programmes [15]. Studies demonstrated that MenACV rollout in the African meningitis belt from 2010 resulted in a dramatic reduction in the incidence of N. meningitidis serogroup A [16-19]. The predominant pathogens causing epidemics in the African meningitis belt are N. meningitidis serogroups C, W and X, and S. pneumoniae [10,20,21]. The objective of this study was to update the status of MenACV in the African meningitis belt from 2010 to 2024.

Methods     

Study, period, population

A cross-sectional study was carried out considering the period of 2010 to 2023. The population of this study was characterized by people living in health districts at the highest risk for meningitis in 26 countries of the African meningitis belt. The 26 countries of the African meningitis are Benin, Burkina Faso, Cameroon, Central Africa Republic, Chad, Cote d´Ivoire, Democratic Republic of Congo, Eritrea, Ethiopia, Ghana, Gambia, Guinea, Guinea Bissau, Kenya, Mali, Mauritania, Niger, Nigeria, Sudan, South Sudan, Rwanda, Senegal, South Sudan, Tanzania, Togo, and Uganda. Health districts at high epidemic risk and burden were selected to introduce MenACV.

Health district prioritization

The selection was made through risk assessment using the district prioritization tool (DPT) developed by WHO. The DPT is a comprehensive and standardized tool that has been developed for meningitis risk assessment in countries of the African meningitis belt. The DPT was used to rank high-risk districts in countries that will conduct MenACV preventive vaccination campaigns and introduce into the routine immunization [14]. The total estimated target population of the African meningitis belt was around 400 million inhabitants. People who were vaccinated with MenACV were aged 1-29 years old during the initial preventive vaccination campaign, representing almost 70% of the total population. Preventive catch-up campaigns were organized for children aged 1-15 years born from the initial campaign and the year of introduction of MenACV into routine immunization. The age groups 1-29 years and 1-15 years were selected because they were the highest risk of meningitis infection caused by N. meningitidis A. For routine immunization schedule, children aged 9-18 months were included.

Strategies to eliminate meningitis epidemics caused by N. Meningitidis A

In 2008 during the African Union summit in Yaoundé, heads of States made a declaration to eliminate meningitis epidemics caused by N. Meningitidis A. WHO recommends strategies to eliminate meningitis epidemics that include ensuring long-term protection against N. Meningitidis A disease with MenACV through mass vaccination campaigns to provide individual and herd protection with at least 90% administrative coverage and at least 60% vaccination survey coverage. All cohorts of children born between the year of initial preventive vaccination campaigns and introduction of MenACV into routine immunization should be cached up with the same vaccination coverage goals as for initial vaccination campaigns. Moreover, MenACV vaccine should be introduced in routine immunization to provide long-term sustainability [5].

From 2010 to 2023 24 countries (Benin, Burkina Faso, Cameroon, Central Africa Republic, Chad, Cote d´Ivoire, Democratic Republic of Congo, Eritrea, Ethiopia, Ghana, Gambia, Guinea, Guinea Bissau, Kenya, Mali, Mauritania, Niger, Nigeria, Sudan, South Sudan, Rwanda, Senegal, South Sudan, and Togo) introduced MenACV through preventive mass vaccination campaigns among them 15 countries (Benin, Burkina Faso, Central African Republic, Chad, Ivory Coast, Eritrea, Gambia, Ghana, Guinea, Guinea Bissau, Mali, Niger, Nigeria, Sudan, and Togo) Introduced it in their routine immunization programme. Tanzania and Rwanda didn´t introduce MenACV. They planned to strengthen surveillance to inform vaccination strategy. Concerning routine immunization, an estimated 56.4% children aged 9 to 18 months were vaccinated from 2016 to 2023 in Benin, Burkina Faso, Central African Republic, Chad, Ivory Coast, Eritrea, Gambia, Ghana, Guinea, Guinea-Bissau, Mali, Niger, Nigeria, Sudan, and Togo (Figure 1). Furthermore, enhancing epidemic response and control, strengthening surveillance and laboratory capacity, and promoting the development and use of affordable multivalent conjugate vaccines are needed. These strategies are also included in the regional framework to defeat meningitis by 2030 in the African region [6].

Data collection and analysis

Non-probability sampling was chosen because all countries that introduced MenACV between 2010 and 2024 were participants. The countries included in this study are in the African meningitis belt, and they introduced MenACV between January 2010 and December 2024. The other African countries are excluded. Moreover, data were collected from the World Health Organization (WHO) and WHO/UNICEF estimates of national immunization coverage (WUENIC) databases, country reports on MenACV, and literature. Descriptive statistic was conducted in this study using Microsoft Excel 2023. The independent variable was MenACV vaccination status of health district (people immunized, immunization coverage). The generalizability was feasible due to the large sample size, and the sample was well-defined.

Results     

Meningococcal serogroup A conjugate vaccine preventive and reactive campaigns 2010-2023

As of 2023, 24 out of the 26 countries of meningitis belt had introduced MenACV through preventive and reactive vaccination campaigns. In addition, Chad and Guinea introduced in 2011, 2012 and 2014 during meningitis epidemics caused by N. meningitidis A recorded in 23 districts. A cumulative total of 289,975,486 (99.8±5.3%) eligible people aged 1-29 years old were immunized with one dose of MenACV. Vaccination coverage varied from 66.7% in Kenya to 107.4% in Ivory Coast. The median was 101%. Eight out of 24 countries didn't conduct a vaccination survey they are Chad, Ethiopia, Ivory Coast, Mauritania, DRC, South Sudan, Uganda and Burundi. The mean of vaccination survey was 91.0±8.9and varied from 69.9% in Nigeria to 99.6% in Eritrea and the median was 89% (Table 1).

Preventive catch-up campaigns 2016-2023 with meningococcal serogroup A conjugate vaccine

The Table 2 shows that 14 countries out of the 24 that initially introduced MenACV conducted catch-up preventive vaccination campaigns for birth cohorts of children aged 1-15 years old born after the initial preventive campaigns. During those vaccination campaigns, 68,403,528 of the target children were vaccinated. The administrative coverage was 101.3% and varied from 92.0% in Gambia to 107.0 in Benin. The regional average vaccination coverage survey result was 92% and varied from 89% in Cameroon and Togo to 97% in Burkina Faso.

Meningococcal serogroup A conjugate vaccine introduce into routine immunization 2016-2023

Fifteen out of 26 countries of the African meningitis belt introduced MenACV into routine vaccination schedule from 2016 to 2023. These countries are Benin, Burkina Faso, Central African Republic, Chad, Ivory Coast, Eritrea, Gambia, Ghana, Guinea, Guinea-Bissau, Mali, Niger, Nigeria, Sudan, and Togo. The age groups varied from 9-18 months. As of 31 December 2023, 49,700,165 children (56.7%) aged 9-18 months have been vaccinated. The average of children vaccinated was 3,313,344, and the median was 2,037,905 (Table 3).

Discussion     

Meningococcal serogroup A conjugate vaccine preventive and reactive campaigns 2010-2023

All 24 countries that have introduced MenACV have achieved the recommended at least 90% administrative coverage and/or at least 60% vaccination coverage, and this result has been demonstrated in the literature. This shows a high level of commitment from countries in the preparation, conduct, and evaluation of activities related to the introduction of MenACV [15,19,21-24]. These results can be explained by high commitment from partners and a high level of acceptance of MenACV by beneficiary communities, which was found by Idoko et al., Okwo-Bele et al., and Sambo et al. [13,25]. Rwanda and Tanzania have not introduced MenACV because the meningitis risk analysis with the DPT tool did not allow the countries to decide to introduce MenACV. However, they planned to strengthen surveillance to have more evidence because the results obtained during the risk analysis were probably due to the poor performance of disease surveillance, including meningitis [14]. Chad and Guinea had to use MenACV to respond to meningitis epidemics caused by N. Meningitidis A when they had not yet introduced it, which helped to stop these epidemics.

Preventive catch-up campaigns 2016-2023 with meningococcal serogroup A conjugate vaccine

Only 14 of the 24 countries in the meningitis belt initially introduced MenACV during initial preventive campaigns or in response to meningitis epidemics caused by N. Meningitidis A in Chad and Guinea. This situation can be explained by one reason: nine countries have not yet decided to introduce MenACV into routine vaccination, which is associated with catch-up vaccination campaigns [6]. These countries are Burundi, DRC, Kenya, Mauritania, Senegal, South Sudan, and Uganda. Cameroon has not yet introduced MenACV into routine vaccination, but has started vaccinating in the Far North region and plans to complete it in 2026 in other districts of the regions located in the African meningitis belt. Thirteen of the 14 countries recorded very good performances with an average administrative vaccination coverage of 99.8% ranging from 88% to 105.3%. The difference can be explained by poor quality of data management during vaccination campaigns. Vaccination coverage varied from 69.9% to 99.6%. These results are good because it was necessary to reach at least 60%. These results are also found in the literature [15,19,21].

Meningococcal serogroup A conjugate vaccine introduced into routine immunization 2016-2023

Routine vaccination programs must achieve at least 90% vaccination coverage of all antigens, including MenACV [6,26,27]. MenACV vaccination coverage has increased from 27% in 2016 to 62% in 2023. There has been a plateau between 2018 and 2023. This performance can be explained by the effect of the response to the COVID-19 pandemic, which has weakened the health system, including the routine vaccination program [6,27]. Also, in general, the performance of the routine vaccination program has also plateaued for a decade, even though MenACV coverage was below the pentavalent 3 and the first dose of measles vaccine, but higher than the second dose of measles vaccine [27]. It is also important to note that many countries were cautious when introducing a new vaccine, and the targets were lower than those expected in the routine vaccination program, thus at least 90%. A lack of robust communication programme may also explain low demand. Success in maintaining long-term herd immunity and eliminating meningitis caused by N. meningitidis A should be achieved with the introduction of MenACV into routine vaccination by the nine remaining countries, because the risk remains in these countries.

Limitations of the study

Data and information used in this study were accurate. This study retrieved accurate data from WUENIC and country reports, WHO AFRO database. The generalizability of this study is feasible due to the large sample size from the 24 countries chosen for this study out of 26 countries of the African meningitis belt. The total estimated target population of the 24 African meningitis belt countries was over 450 million persons at highest risk of meningitis. The target population of this study was large and representative because a nonprobability sampling method was used. Therefore, the findings of this study can be generalized. Vaccination coverage survey was not conducted in all the 24 countries after initial and catch-up preventive vaccination campaigns. However, we have estimated the average vaccination coverage because over 50% of countries conducted this activity.

Conclusion     

From 2010 to 2023, over 408 million people aged 9 months to 29 years old have been vaccinated successfully with MenACV in 24 countries of the African meningitis belt through vaccination campaigns and routine immunization. Vaccination coverage in routine was less than 90% for children aged 9-18 months through routine immunization in 15 countries. Elimination of meningitis caused by N. meningitidis A will be sustained with the coverage obtained during vaccination campaigns and routine immunization. Nine countries have not yet introduced MenACV, and they can be pockets that can jeopardize efforts made to eliminate meningitis epidemics caused by N. meningitidis A. It is relevant to introduce MenACV in these countries or the new multivalent meningococcal conjugate ACWXY vaccine (Men5CV). To make Africa free of meningitis by 2030, it is important for the 15 countries that introduced MenACV in their routine immunization schedule to switch to Men5CV and conduct a preventive vaccination campaign with it in the highest risk districts.

Competing interests     

The authors delcare no competing inetrests.

Authors' contributions     

All authors contributed to the selection of the topic, protocol development, data collection and analysis, interpretation of results, discussion, and conclusion. All the authors read and approved the final version of this manuscript.

Acknowledgments     

We would like to express our gratitude to The WHO AFRO Member States, GAVI, BMGF, UNICEF, CDC, SII.

Tables and figure     

Table 1: preventive and reactive campaigns with meningococcal serogroup A conjugate vaccine from 2010 to 2023

Table 2: catch-up preventive campaigns with meningococcal serogroup A conjugate vaccine from 2010 to 2023

Table 3: number of children immunized in routine immunization 2016-2023

Figure 1: status of meningococcal A conjugate vaccine rollout in the meningitis belt 2010-2023

References