Progress Toward Measles Preelimination — African Region, 2011–2012

Balcha G. Masresha, MD1, Reinhard Kaiser, MD2, Messeret Eshetu, MD2, Reggis Katsande, MBA1, Richard Luce, MD3, Amadou Fall, MD4, Annick R.G.A. Dosseh, PhD4, Boubker Naouri, MD5, Charles R. Byabamazima, MD2, Robert Perry, MD6, Alya J. Dabbagh, PhD6, Peter Strebel, MD6, Katrina Kretsinger, MD5, James L. Goodson, MPH5, Deo Nshimirimana, MD1 (Author affiliations at end of text)

In 2008, the 46 member states of the World Health Organization (WHO) African Region (AFR) adopted a measles preelimination goal to reach by the end of 2012 with the following targets: 1) >98% reduction in estimated regional measles mortality compared with 2000, 2) annual measles incidence of fewer than five reported cases per million population nationally, 3) >90% national first dose of measles-containing vaccine (MCV1) coverage and >80% MCV1 coverage in all districts, and 4) >95% MCV coverage in all districts by supplementary immunization activities (SIAs) (1). Surveillance performance objectives were to report two or more cases of nonmeasles febrile rash illness per 100,000 population, one or more suspected measles cases investigated with blood specimens in ≥80% of districts, and 100% completeness of surveillance reporting from all districts (1). This report updates previous reports (2–4) and describes progress toward the measles preelimination goal during 2011–2012. In 2012, 13 (28%) member states had >90% MCV1 coverage, and three (7%) reported >90% MCV1 coverage nationally and >80% coverage in all districts. During 2011–2012, four (15%) of 27 SIAs with available information met the target of >95% coverage in all districts. In 2012, 16 of 43 (37%) member states met the incidence target of fewer than five cases per million, and 19 of 43 (44%) met both surveillance performance targets. In 2011, the WHO Regional Committee for AFR established a goal to achieve measles elimination* by 2020. To achieve this goal, intensified efforts to identify and close population immunity gaps and improve surveillance quality are needed, as well as committed leadership and ownership of the measles elimination activities and mobilization of adequate resources to complement funding from global partners.

Immunization Activities

WHO and the United Nations Children's Fund (UNICEF) use data from administrative records and surveys reported annually by member states through the Joint Reporting Form (JRF)† to estimate MCV1 coverage among children aged 1 year. Since 2003, member states also have reported the proportion of districts reaching ≥80% MCV1 coverage. Estimates of MCV1 coverage in AFR were 74% in 2011 and 73% in 2012 (Table 1). The number of member states with >90% MCV1 coverage was 14 (30%) in 2011 and 13 (28%) in 2012 (Table 1). MCV1 coverage was >90% nationally and >80% in all districts in four (9%) of 44 member states reporting district coverage data in 2011 and three (7%) of 44 in 2012. By the end of 2012, 12 (26%) member states had introduced a second dose of measles containing-vaccine (MCV2) into the routine vaccination schedule.

During 2011–2012, approximately 133 million children were vaccinated during 35 measles SIAs (Table 2). Of these SIAs, 23 (66%) had >95% national level administrative coverage, and of the 27 with available information, four (15%) had >95% MCV administrative coverage in all districts. Among the 20 SIAs that had a post-SIA coverage survey, 19 (95%) had lower coverage estimated by survey than by administrative report (Table 2). At least one other child health intervention was delivered in 23 (66%) SIAs (Table 2).

Surveillance Activities

In 2012, the WHO Global Measles and Rubella Laboratory Network§ supported standardized methods and quality assurance measures in 44 laboratories in 42 member states. Measles case-based surveillance includes individual case investigation and blood specimen collection for laboratory testing (5). Suspected measles cases are confirmed on the basis of laboratory findings, an epidemiologic link, or clinical criteria.¶ During outbreaks, nasopharyngeal swab specimens are collected to identify measles virus genotypes.

During 2011–2012, 43 (93%) member states reported measles case-based surveillance data, and all member states reported annually through the JRF the number of measles cases. In 2012, 19 (44%) member states met both targets of two or more cases of nonmeasles febrile rash illness per 100,000 population and one or more suspected measles cases investigated with blood specimens in ≥80% of districts, 14 (33%) met one of the targets but did not meet the other target, and 10 (23%) did not meet either of the targets (Figure).

Measles Incidence and Measles Virus Genotypes

On the basis of measles case-based surveillance data, the number of confirmed measles cases decreased from 43,800 in 2011 to 25,905 in 2012, and confirmed measles incidence per million population decreased from 50.4 to 29.0 (Table 1). In 2012, 16 of 43 (37%) member states met the incidence target of fewer than five cases per million. The number of measles cases reported through the JRF was 194,364 in 2011 and 106,052 in 2012. Measles incidence per million population was 223.6 in 2011 and 118.8 in 2012 (Table 1). During 2011–2012, measles virus genotype results were reported from 20 (43%) member states; the predominant genotypes detected were B3 in all 20 reporting member states; B2 in Angola, the Democratic Republic of the Congo (DRC), and Namibia; and D4 in Uganda.**

Discussion

Despite substantial progress and an 88% reduction in estimated measles mortality in AFR (from 354,900 to 41,400) during 2000–2012 (6), the measles 2012 preelimination goal was not reached. Major outbreaks occurred during 2009–2010, and reported measles cases have remained above the historic low of 37,012 cases in 2008 (2,3). During 2011–2012, large outbreaks occurred in a small number of member states; 89% of cases in 2011 were from four member states (Chad, DRC, Nigeria, and Zambia), and 88% of cases in 2012 were from five member states (Angola, Burkina Faso, DRC, Ethiopia, and Nigeria). Various outbreak investigation activities conducted in these outbreaks indicated that the primary causes were an accumulation of susceptible older children and adolescents, shifting susceptibility towards older age groups, and continued gaps in reaching all children with 2 doses of measles vaccine at national and subnational levels through routine vaccination or periodic follow-up SIAs.

Annual measles cases in AFR reported through the JRF have been consistently higher than those reported through case-based surveillance. According to WHO guidelines, the total number of confirmed cases reported to the measles case-based surveillance system should match the total number of measles cases reported through the JRF. In 2012, 13 member states reported considerably more cases through the JRF than case-based surveillance.†† These differences might be attributable to classification errors, reporting errors, difficulties in capturing large outbreaks through the case-based system, or reliance on aggregate summary reporting of notifiable diseases through the Integrated Disease Surveillance and Response system.§§ Limited implementation of case-based surveillance in some health facilities, incomplete preparation and reporting of line lists during outbreaks, and insufficient personnel to enter all surveillance data into databases might contribute to underreporting through measles case-based surveillance.

The proportion of member states meeting both case-based surveillance performance indicators increased from 35% in 2009 (3) to 44% in 2012. Measles surveillance systems in member states not attaining objectives for surveillance indicators might lack the sensitivity to allow rapid detection and response to outbreaks. Monitoring district-level surveillance performance indicators can help member states to identify and prioritize support for areas needing to improve performance; conducting adequate outbreak investigations could rapidly identify and characterize outbreaks and guide response activities.

The findings in this report are subject to at least three limitations. First, MCV coverage estimates likely include errors from inaccurate estimates of the size of target populations, inaccurate reporting of doses delivered, and inclusion of SIA doses given to children outside the target age group. Second, surveillance data underestimate the actual number of cases because not all patients with measles seek care and not all of those who seek care are reported. Finally, some member states maintain multiple reporting systems for measles and might, like DRC, report in the JRF aggregate, unconfirmed cases rather than confirmed cases generated from case-based surveillance.

The Global Vaccine Action Plan and the Measles and Rubella Initiative¶¶ Strategic Plan provide key strategies and targets for measles elimination in five regions by 2020 (7,8). In September 2011, the WHO Regional Committee for AFR established a goal of measles elimination by 2020 (9). The regional strategic plan for measles elimination (2012–2020) outlines the key programmatic focus, and the approaches to follow to achieve measles elimination. In AFR member states, intensified efforts to increase coverage with 2 doses of MCV include implementing updated policies to decrease missed opportunities, including opening multidose vials even when few eligible children are present, immunizing unvaccinated children aged ≤5 years through routine immunization services, sustaining the implementation of the "reaching every district" approach (10), using SIAs to improve routine immunization services, and introducing a second dose in the routine immunization schedule once criteria are met.*** To ensure high population immunity, member states should also conduct high-quality, well-monitored SIAs that are routinely evaluated through coverage surveys. SIA target age groups should be based on national measles epidemiology determined by surveillance and immunization data.

Member states are encouraged to mobilize adequate additional resources to complement the funding from global partners to achieve their goal of measles elimination. In addition to funding from the Measles and Rubella Initiative and other organizations, the GAVI Alliance is providing funding to support the introduction of a second dose of measles vaccine in routine immunization; measles SIAs in Chad, DRC, Ethiopia, and Nigeria; and the introduction of rubella vaccine through wide–age range measles-rubella vaccination campaigns.

1Immunization and Vaccine Development Program, World Health Organization (WHO) Regional Office for Africa, Brazzaville, Congo; 2Expanded Program on Immunization, WHO Regional Office for Africa, Inter-Country Support Team, Harare, Zimbabwe; 3Expanded Program on Immunization, WHO Regional Office for Africa, Inter-Country Support Team, Libreville, Gabon; 4Expanded Program on Immunization, WHO Regional Office for Africa, Inter-Country Support Team, Ouagadougou, Burkina Faso; 5Global Immunization Division, Center for Global Health, CDC; 6Department of Immunization, Vaccines, and Biologicals, WHO, Geneva, Switzerland (Corresponding author: Reinhard Kaiser, kaisere@who.int, +47-241-38114)

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