Progress Toward Measles Elimination — African Region, 2017–2021

Abstract

Worldwide, measles remains a major cause of disease and death; the highest incidence is in the World Health Organization African Region (AFR). In 2011, the 46 AFR member states established a goal of regional measles elimination by 2020; this report describes progress during 2017–2021. Regional coverage with a first dose of measles-containing vaccine (MCV) decreased from 70% in 2017 to 68% in 2021, and the number of countries with ≥95% coverage decreased from six (13%) to two (4%). The number of countries providing a second MCV dose increased from 27 (57%) to 38 (81%), and second-dose coverage increased from 25% to 41%. Approximately 341 million persons were vaccinated in supplementary immunization activities, and an estimated 4.5 million deaths were averted by vaccination. However, the number of countries meeting measles surveillance performance indicators declined from 26 (62%) to nine (22%). Measles incidence increased from 69.2 per 1 million population in 2017 to 81.9 in 2021. The number of estimated annual measles cases and deaths increased 22% and 8%, respectively. By December 2021, no country in AFR had received verification of measles elimination. To achieve a renewed regional goal of measles elimination in at least 80% of countries by 2030, intensified efforts are needed to recover and surpass levels of surveillance performance and coverage with 2 MCV doses achieved before the COVID-19 pandemic.

Introduction

Measles remains a major cause of disease and death worldwide, with the highest numbers of cases and deaths occurring in the World Health Organization (WHO) African Region (AFR) (1). In 2011, the 46 member states* in AFR established a goal of measles elimination^† by 2020, using a regional strategy to achieve 1) ≥95% coverage with 2 doses of measles-containing vaccine (MCV) at national and district levels through routine or supplementary immunization activities (SIAs)^§; 2) confirmed measles incidence of <1 case per 1 million population in all countries; and 3) case-based surveillance systems that meet performance indicator targets^¶ (2). This report describes progress toward the regional measles elimination goal during 2017–2021 and updates the previous report (3).

Methods

WHO and UNICEF estimate coverage with the first and second MCV doses (MCV1 and MCV2, respectively) delivered through routine immunization services** for all countries, using annual administrative coverage data (number of doses administered divided by the estimated target population), national coverage estimates, and vaccination coverage surveys (4). AFR countries conduct case-based measles surveillance,^†† with suspected cases identified using a case investigation form. Suspected cases are laboratory-confirmed based on serologic testing, epidemiologic linkage to a confirmed case, or clinical criteria (5). Serologic testing is performed within the regional laboratory network, which consists of 52 laboratories in 43 countries, supported by the WHO Global Measles and Rubella Laboratory Network.^§§ Two principal surveillance performance indicators used to monitor surveillance performance are 1) identification of two or more discarded cases of nonmeasles febrile rash illness per 100,000 population annually, and 2) collection of a blood specimen from at least one suspected measles case in at least 80% of districts annually (5). A previously described model for estimating measles cases and deaths was updated with measles case data and United Nations population estimates data during 2000–2021^¶¶ (6), and regional estimates were calculated. This activity was reviewed by CDC and was conducted consistent with applicable federal laws and CDC policy.***

Results

Immunization Activities

During 2017–2019, estimated regional MCV1 coverage remained stable at 70% but decreased to 68% in 2021 (Figure 1). Six countries reported ≥95% MCV1 coverage in 2017 (Botswana, Cabo Verde, Ghana, Rwanda, Seychelles, and Zambia) and in 2019 (Botswana, Cabo Verde, Mauritius, Rwanda, São Tomé and Príncipe, and Seychelles); however, only two countries (Botswana and Cabo Verde) reported ≥95% MCV1 coverage in 2021 (Table). The number and percentage of countries providing MCV2 increased from 27 (57%) to 38 (81%) and estimated regional MCV2 coverage increased from 25% to 41%. Three countries (Mauritius, Rwanda, and Seychelles) reported ≥95% MCV2 coverage in 2017; this decreased to two countries (Mauritius and Seychelles) in 2019, and none in 2021. Approximately 341 million persons received MCV during 69 SIAs conducted in 41 countries (Supplementary Table, https://stacks.cdc.gov/view/cdc/132420). Reported administrative coverage was ≥95% in 42 (61%) SIAs. Only two of 29 post-SIA coverage surveys reported ≥95% coverage.

Surveillance Activities

During 2017–2021, 42 (88%) countries reported weekly case-based measles surveillance data to the WHO African Regional Office. The number and percentage of countries that met both surveillance indicators decreased from 26 (62%) in 2017 to 19 (45%) in 2019 and to nine (22%) in 2021 (Figure 2).

Reported Measles Incidence and Measles Virus Genotypes

From 2017 to 2019, the number of reported measles cases^††† increased more than sevenfold, from 72,603 to 618,595, then declined to 88,789 in 2021 (Figure 1). During 2017–2021, three countries accounted for 87% (885,934) of confirmed cases reported: the Democratic Republic of Congo (DRC) (584,578; 57%), Madagascar (235,483; 23%), and Nigeria (65,873; 6%). Confirmed annual measles incidence^§§§ increased from 69.2 cases per 1 million population in 2017 to 559.8 in 2019 and decreased to 81.9 in 2021 (Table).

The regional laboratory network processed blood specimens from 46,501 suspected measles cases in 2017, 61,636 in 2019, and 41,291 in 2021. Measles genotypes were obtained from confirmed measles cases in 16 (34%) countries; genotypes B3 (180; 64%) and D8 (103; 36%)^¶¶¶ were detected.

Measles Case and Mortality Estimates

Using the previously described model, the estimated number of measles cases in AFR increased 22% from 3,623,869 in 2017 to 4,430,595 in 2021, peaking at 6,377,451 in 2019. The estimated number of annual measles deaths increased from 61,166 in 2017 to 104,543 in 2019 before decreasing to 66,230 in 2021. During 2017–2021, an estimated 4.5 million measles deaths were prevented by measles vaccination.

Regional Verification of Measles Elimination

The African Regional Commission for the Verification of Measles Elimination (RVC) was established in 2017. During 2017–2021, 10 countries established national verification committees to support documentation of progress toward measles elimination. The African RVC met during 2018–2019**** but not during 2020–2021 because many national immunization programs were fully engaged in the COVID-19 pandemic response. By December 2021, no country in AFR had received verification of measles elimination.

Discussion

The WHO AFR has made substantial progress in reducing measles cases and deaths since 2000 (1). However, the 2020 measles elimination goal was not attained, and the COVID-19 pandemic further exacerbated challenges associated with implementing the regional strategy (7). After a review in 2021, the Regional Strategic Plan for Immunization 2021–2030 reset the goal to achieve measles elimination in at least 80% of countries by 2030 (8).

During 2017–2021, regional MCV1 coverage remained stable at 68%–70%, but below the level of ≥95% necessary to achieve and sustain measles elimination; regional coverage was largely driven by low coverage in populous countries like DRC, Ethiopia, and Nigeria, which account for nearly 40% of the region’s population. Eleven countries introduced MCV2, but no AFR country reached 95% MCV2 coverage. Worldwide, among all children who did not receive MCV1 in 2021, approximately 50% (12.3 million) lived in AFR countries.^†††† An additional 21.1 million children in the region missed MCV2, leaving a large population at increased risk for measles disease and outbreaks. Tailored efforts must be made to monitor this risk and reach unvaccinated and undervaccinated children through intensified immunization activities, increased vaccine demand, and improved delivery of MCV at both fixed and outreach sites. Periodic, preventive SIAs remain a critical tool for reaching unvaccinated and undervaccinated children, particularly in settings where MCV coverage is <95%, and immunization data quality is unreliable (9).

Surveillance quality improved in 2017, with 26 countries attaining both indicator targets compared with 19 countries in 2016 (3). However, only 19 countries met both targets in 2019, and performance further declined during the COVID-19 pandemic (7), with only nine countries meeting both targets in 2021 and significant reductions in reported cases and specimens processed by the regional laboratory network. These declines might be further compounded by the forecasted reduction in resources from the Global Polio Eradication Initiative for vaccine-preventable disease surveillance infrastructure as part of the Polio Endgame Strategy 2019–2023.^§§§§

Measles incidence continued to increase during 2017–2021, reaching a peak in 2019 amid a global resurgence (10). In 2021, reported cases were still 22% higher than in 2017, with DRC and Nigeria accounting for nearly three quarters (73%) of the 88,789 reported cases. The number of cases estimated by modeling in 2021 was 4.4 million, indicating underperforming surveillance systems. Lessons learned from explosive outbreaks in 2019 in DRC and Madagascar highlight the need to conduct timely preventive SIAs, implement high-quality surveillance, and ensure outbreak preparedness, including availability of resources for rapid response. Beginning in 2020, the WHO African Regional Office has supported priority countries in building capacity and developing and implementing measles outbreak preparedness and response plans.

Limitations

The findings in this report are subject to at least three limitations. First, immunization coverage estimates are based primarily on administrative data, which might contain inaccuracies resulting from errors in recording doses administered or in population estimates. Second, cases and incidence might be underestimated because of inaccuracies in population estimates, variation in measles surveillance performance and data quality among countries, and because not all persons with suspected measles seek care and thus are not identified by the health system. Finally, the measles case and mortality estimates might contain inaccuracies resulting from errors in the data inputs and are subject to the inherent uncertainty of modeling estimates.

Implications for Public Health Practice

Despite not reaching the 2020 elimination goal, implementation of measles elimination strategies substantially reduced measles morbidity and mortality in AFR, with measles vaccination averting approximately 19.5 million deaths during 2000–2021 (1). However, an estimated 33.4 million children in the region still did not receive 1 or both MCV doses in 2021, highlighting the urgent need to accelerate recovery of immunization systems and prevention of outbreaks after the COVID-19 pandemic. Country progress toward measles elimination is an impact indicator within the Immunization Agenda 2021–2030 and represents an opportunity to garner political commitment and mobilize resources. Achieving measles elimination in 80% of countries in AFR by 2030 will require intensified action to attain ≥95% coverage with 2 MCV doses at national and district levels, to strengthen and rebuild high-quality surveillance systems, and to mitigate the risk for outbreaks.