Studies on informal settlements in sub-Saharan Africa have questioned the health benefits of urban residence, but this should not suggest that informal settlements (within cities and across cities and/or countries) are homogeneous. They vary in terms of poverty, pollution, overcrowding, criminality, and social exclusion. Moreover, while some informal settlements completely lack public services, others have access to health facilities, sewers, running water, and electricity. There are few comparative studies that have looked at informal settlements across countries accounting for these contextual nuances. In this paper, we comparatively examine the differences in child vaccination rates between Nairobi and Ouagadougou’s informal settlements. We further investigate whether the identified differences are related to the differences in demographic and socioeconomic composition between the two settings. We use data from the Ouagadougou and Nairobi Urban Health and Demographic Surveillance Systems (HDSSs), which are the only two urban-based HDSSs in Africa. The results show that children in the slums of Nairobi are less vaccinated than children in the informal settlements in Ouagadougou. The difference in child vaccination rates between Nairobi and Ouagadougou informal settlements are not related to the differences in their demographic and socioeconomic composition but to the inequalities in access to immunization services.
We use data from the Ouagadougou and Nairobi Urban Health and Demographic Surveillance Systems (HDSSs), which are the only two urban-based HDSSs in Africa. Both are research and interventions platforms on population and health issues. The Ouagadougou HDSS was established in 2008 in five neighborhoods of the city.20 Two of these neighborhoods (Kilwin and Tanghin) are official districts, with full access to municipal services. The remaining three neighborhoods (Nonghin, Polesgo, and Nioko 2), whose data are used in this comparative study, are unplanned. These neighborhoods widely known as the “non loti” (literally “unloted” zones) are located at the urban periphery of the city, pushing the city’s boundaries further into the surrounding villages. They are governed by traditional land tenure systems and, until recently, were not served by municipal electricity and water services. Houses in these areas are mostly built from clay bricks. Households are usually small, made of single men or young nuclear families, who went there in search of affordable housing. These young families build houses in the hope that they will eventually own the land when the city’s authorities formally allocate the land. The population density is not necessarily high in these areas (42 inhabitants per hectare). With regard to social characteristics, people living in Ouagadougou informal areas are more often poorer, uneducated, and born in rural areas compared to people living in formal areas.21 In June 2013, the population covered by the Ouagadougou HDSS in the three informal settlements totaled 46,216 residents (defined as persons present in the area for at least 6 months). The Nairobi Urban HDSS (NUHDSS) has been following residents of two slums in Nairobi city—Korogocho and Viwandani—since 2002. As of 2013, the NUHDSS has been following over 70,000 individuals, residing in over 25,000 households. Compared to the Ouagadougou informal settlements, those in Nairobi are more crowded (over 730 people per hectare). The two slums are located less than 10 km from the Central Business District (CBD) of Nairobi, Kenya’s capital city, and about 7 km from each other. They are characterized by a lack of basic infrastructure, high unemployment rates, poor water and environmental sanitation, poor housing, insecurity, violence, and poor health indicators.10 , 22 Consistent with the perspective on heterogeneity of settlements, the socioeconomic status and demographic composition of the two slums differ from each other. Located in the industrial area, Viwandani residents have relatively higher levels of education and employment as it attracts migrant workers to the surrounding industries. It therefore has higher socioeconomic status than Korogocho. Additionally, it consists of higher prevalence of single-person households. Korogocho on the other hand has a more stable population, with residents having generally lived there for a long period. Korogocho also has greater co-residence of spouses, and the family size is generally bigger.23 Residents of both Nairobi settlements are mainly rural–urban migrants and contrary to Ouagadougou’s informal settlements, they undergo rapid renewal of their population (about 21 % per year) due to high circular migration patterns.24 In the Ouagadougou HDSS, immunization data are updated every round while in the case of Nairobi, they originate from the Maternal and Child health follow-up study nested in the NUHDSS. Since September 2006, all children born to NUHDSS residents were recruited into this study, and vaccination details were collected in the first visit about 4 months after birth with follow-up visits repeated thereafter at 4-month intervals. The vaccination status of children is considered as at December 31, 2011 and analyzed for children 12 to 59 months who, according to the WHO time frame, should have received all the necessary vaccines before their first birthday.25 This age group was chosen in several studies to analyze the full immunization of children.26 – 29 The sample size is 3103 children in Ouagadougou and 1369 in Nairobi.
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