A scorecard of progress towards measles elimination in 15 west African countries, 2001-19: a retrospective, multicountry analysis of national immunisation coverage and surveillance data

Abstract

Background: The WHO Regional Office for the Africa Regional Immunization Technical Advisory Group, in 2011, adopted the measles control and elimination goals for all countries of the African region to achieve in 2015 and 2020 respectively. Our aim was to track the current status of progress towards measles control and elimination milestones across 15 west African countries between 2001 and 2019.

Methods: We did a retrospective multicountry series analysis of national immunisation coverage and case surveillance data from Jan 1, 2001, to Dec 31, 2019. Our analysis focused on the 15 west African countries that constitute the Economic Community of West African States. We tracked progress in the coverage of measles-containing vaccines (MCVs), measles supplementary immunisation activities, and measles incidence rates. We developed a country-level measles summary scorecard using eight indicators to track progress towards measles elimination as of the end of 2019. The summary indicators were tracked against measles control and elimination milestones.

Findings: The weighted average regional first-dose MCV coverage in 2019 was 66% compared with 45% in 2001. 73% (11 of 15) of the west African countries had introduced second-dose MCV as of December, 2019. An estimated 4 588 040 children (aged 12-23 months) did not receive first-dose MCV in 2019, the majority (71%) of whom lived in Nigeria. Based on the scorecard, 12 (80%) countries are off-track to achieving measles elimination milestones; however, Cape Verde, The Gambia, and Ghana have made substantial progress.

Interpretation: Measles will continue to be endemic in west Africa after 2020. The regional measles incidence rate in 2019 was 33 times the 2020 elimination target of less than 1 case per million population. However, some hope exists as countries can look at the efforts made by Cape Verde, The Gambia, and Ghana and learn from them.

Funding: None.

Figure 1

MCV1 coverage, MCV2 introduction, reach of supplementary immunisation activities, and unvaccinated children in west Africa, 2001–19 (A) Regional median and weighted mean MCV1 coverage in west Africa between 2001 and 2019. Mean MCV1 coverage weighted by each country's total surviving infant population as a proportion of the surviving infant population in west Africa per year. (B) MCV2 introduction in west Africa, 2001–19. (C) Cumulative population targeted and reached by supplementary immunisation activities in west Africa, 2001–19. (D) Number of west African children who did not receive MCV1 vaccination per country in west Africa in 2019; the size of each bubble corresponds to the absolute number of unvaccinated children per country in 2019. MCV1=first dose of measles-containing vaccine. MCV2=second dose of measles-containing vaccine.

Figure 2

Map of west Africa showing disaggregated MCV1 coverage (%) by subnational administrative areas (regions or states) across the 15 ECOWAS countries The most recently available, disaggregated national survey data used per country. Benin (DHS 2017–18), Burkina Faso (DHS 2010), Cape Verde (DHS 2005), Côte d’Ivoire (MICS 2016), Gambia (MICS 2018), Ghana (DHS 2014), Guinea (DHS 2018), Guinea Bissau (MICS 2014), Liberia (DHS 2013), Mali (DHS 2018), Niger (DHS 2012), Nigeria (DHS 2018), Senegal (DHS 2017), Sierra Leone (MICS 2017), and Togo (DHS 2013–14). DHS=Demographic and Health Survey. ECOWAS=Economic Community of West African States. MCV1=first dose of measles-containing vaccine. MICS=Multiple Indicator Cluster Survey.

Figure 3

Measles cases and measles incidence rate per million population in west Africa, 2001–19 (A) Cumulative number of reported measles cases per year. The number of measles cases for Togo during this period were quite small compared with other countries, thus, they are not visible in this figure. (B) Measles incidence rate per million population between 2001 and 2019 based on available country-level cases reported to WHO in 15 west African countries. Cape Verde consistently reported the lowest measles incidence rate of zero per million population. Country-level population was based on the UN World Population Prospects 2019.

Figure 4

Relationship between MCV1 coverage, SIAs, and measles incidence rate per million population in west Africa, 2001–19 (A) Relationship between weighted mean MCV1 coverage and weighted mean regional measles incidence rate in west Africa, 2001–19. (B) Relationship between measles SIAs and weighted mean measles incidence rate in west Africa, 2001–19. Some countries did more than one SIA per year. MCV1=first dose of measles-containing vaccine. SIAs=supplementary immunisation activities.

Figure 5

Scorecard summary showing achievement of measles elimination milestones across countries in the west African region JEE=Joint External Evaluation. MCV1=first dose of measles-containing vaccine. MCV2=second dose of measles-containing-vaccine. *MCV1 and MCV2 coverage categories: dark green=≥90% in 2015 and ≥95% in 2019; light green=80–89% in 2015 and 80–94% in 2019; yellow=50–79%; and red=≤50%. As of December, 2019, Benin, Côte d’Ivoire, Guinea, and Guinea-Bissau had not yet commenced MCV2 immunisation. †Intracountry geographical equity gap categories: dark green=≤20% points and red=>20% points. ‡Measles incidence rate per million categories: dark green=<5 cases per million in 2015 and <1 case per million in 2019; light green=5–9 cases per million in 2015 and 1–4 cases per million in 2019; yellow=10–19 cases per million in 2015 and 5–9 cases per million in 2019; and red=>20 cases per million in 2015 and >10 cases per million in 2019. §JEE categories: red=1; yellow=2–3; and dark green=4–5. ¶Country-level measles scorecard categories: dark green=achieved 6–8 of the 8 measles summary indicators; yellow=achieved 3–5 of the 8 measles summary indicators; and red=achieved only 1 or 2 of the 8 measles summary indicators. ||JEE yet to be done.