MEASLES IN AFRICA, 2009-2010/ LA ROUGEOLE EN AFRIQUE, 2009-2010

Wednesday, 30th of March 2011

MEASLES IN AFRICA/ LA ROUGEOLE EN AFRIQUE

Measles outbreaks and progress towards meeting measles pre-elimination goals: WHO African Region, 2009–2010

From the Weekly Epidemiological Record, in English and French:

Text and figures at http://www.who.int/wer/2011/wer8614.pdf

From the Morbidity and Mortality Weekly Report, in English

Text and figures at http://www.cdc.gov/mmwr/preview/mmwrhtml/mm6012a3.htm?s_cid=mm6012a3_w

Editorial Note, MMWR:

During 2001--2008, AFR countries made remarkable progress in reducing measles mortality and morbidity by increasing MCV1 coverage and periodic SIAs (2). However, since reaching an historic low of 32,278 reported cases in 2008, a resurgence of measles led to multiple large outbreaks during 2009--2010, despite increases in reported MCV1 coverage, indicating the fragility of the progress (Figure 1). Suboptimal routine and SIA vaccination coverage led to an increasing number of susceptible persons over a prolonged period of low incidence, allowing some children to remain susceptible as they grew older. Outbreak cases occurring among older children and young adults suggest some progress in reducing measles incidence together with long-standing gaps in vaccination activities. In countries with large outbreaks occurring primarily among children aged <5 years, substantial numbers of children were missed by both routine vaccination and SIAs in recent years. In these countries, estimated MCV1 coverage remains suboptimal and reviews of vaccination services are needed to identify programmatic reasons for nonvaccination (9). Detailed outbreak investigations are recommended to describe the epidemiology of an outbreak, guide rapid ORI, and determine the likely cause of the outbreak (e.g., failure to vaccinate) (1).

The findings in this report are subject to at least two limitations. First, underreporting of measles cases and low sensitivity of measles case-based surveillance in some countries likely led to underestimates of measles incidence. Second, SIA administrative coverage >100% suggests inaccurate and inflated reported coverage (9).

Although post-SIA coverage surveys are recommended, only five of 31 countries implemented a post-SIA coverage survey during 2009--2010. Estimates of vaccination coverage from population-based coverage surveys are key inputs to determine the susceptibility profile of a population. In addition, reliable coverage estimates can help identify areas of low coverage so that program managers can better prioritize and more efficiently use resources. Even though AFR reported MCV coverage has increased continuously and the quality of measles surveillance has improved, subsequent measles outbreaks raise doubts concerning the accuracy and reliability of reported coverage and surveillance data. WHO-recommended methods for improving the accuracy of monitoring measles vaccination programs and post-SIA surveys to estimate coverage should be implemented routinely (1).

The 2009--2010 outbreaks highlight the need for full implementation of regional strategies, with an emphasis on improving vaccination coverage through routine immunization services and SIAs in every district, and introduction of MCV2 into routine immunization services in eligible countries (1). National immunization program policies and delivery systems should be reviewed to ensure access to the recommended 2 doses of MCV by all eligible children. Communication strategies should be identified to ensure vaccination acceptance and demand among all segments of the population. Renewed dedication by donors and governments is needed to ensure that national multiyear plans, budgetary line items, and financial commitments exist for routine immunization services and measles control activities.