LOCAL DISCREPANCIES IN MEASLES VACCINATION OPPORTUNITIES: RESULTS OF POPULATION-BASED SURVEYS IN SUB-SAHARAN AFRICA

Saturday, 22nd of March 2014

[source]BMC Public Health[|source]

In order to sustain gains in measles control and further reduce mortality, an understanding of whether each of the measles vaccination opportunities reach children is essential. Vaccination coverage is the key indicator to measure the progress of measles control. Ministries of Health report annual administrative coverage based on population estimates. In many contexts, however, population estimates, are often not up-to-date, resulting in biased or inaccurate estimates. Consequently, population-based surveys are often the best available means to estimate vaccination coverage at both local and national levels.

 

In this paper, the authors report on the data collected from household-based coverage surveys conducted after measles outbreak response vaccination campaigns in several countries in sub-Saharan Africa. Although the main objective of the post campaign coverage surveys was to estimate vaccination coverage of the outbreak response immunization campaign, the authors use this data to estimate measles vaccine coverage through previous vaccination opportunities: in routine EPI, supplemental immunization, or outbreak response immunization campaigns. Detailed report results, discussion and conclusions is accessible at:  http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3938072/

 

ABSTRACT

BACKGROUND: The World Health Organization recommends African children receive two doses of measles containing vaccine (MCV) through routine programs or supplemental immunization activities (SIA). Moreover, children have an additional opportunity to receive MCV through outbreak response immunization (ORI) mass campaigns in certain contexts. Here, we present the results of MCV coverage by dose estimated through surveys conducted after outbreak response in diverse settings in Sub-Saharan Africa.

METHODS: We included 24 household-based surveys conducted in six countries after a non-selective mass vaccination campaign. In the majority (22/24), the survey sample was selected using probability proportional to size cluster-based sampling. Others used Lot Quality Assurance Sampling.

RESULTS: In total, data were collected on 60,895 children from 2005 to 2011. Routine coverage varied between countries (>95% in Malawi and Kirundo province (Burundi) while <35% in NDjamena (Chad) in 2005), within a country and over time. SIA coverage was <75% in most settings. ORI coverage ranged from >95% in Malawi to 71.4% [95% CI: 68.9-73.8] in NDjamena (Chad) in 2005.

In five sites, >5% of children remained unvaccinated after several opportunities. Conversely, in Malawi and DRC, over half of the children eligible for the last SIA received a third dose of MCV.

CONCLUSIONS: Control pre-elimination targets were still not reached, contributing to the occurrence of repeated measles outbreak in the Sub-Saharan African countries reported here. Although children receiving a dose of MCV through outbreak response benefit from the intervention, ensuring that programs effectively target hard to reach children remains the cornerstone of measles control.