Childhood vaccination timeliness following maternal migration to an informal urban settlement in Kenya

Julia M Porth; Abram L Wagner; Emily Treleaven; Nancy L Fleischer; Martin K Mutua; Thomas M Braun; Matthew L Boulton

doi:10.1016/j.vaccine.2021.12.017

Childhood vaccination timeliness following maternal migration to an informal urban settlement in Kenya

Vaccine. 2022 Jan 28;40(4):627-639. doi: 10.1016/j.vaccine.2021.12.017. Epub 2021 Dec 21.

Authors

Julia M Porth¹, Abram L Wagner², Emily Treleaven³, Nancy L Fleischer⁴, Martin K Mutua⁵, Thomas M Braun⁶, Matthew L Boulton⁷

Affiliations

¹ Department of Epidemiology, School of Public Health, University of Michigan, USA; Global Institute for Vaccine Equity, University of Michigan, USA. Electronic address: jmporth@umich.edu.
² Department of Epidemiology, School of Public Health, University of Michigan, USA; Global Institute for Vaccine Equity, University of Michigan, USA.
³ Institute for Social Research, University of Michigan, USA.
⁴ Department of Epidemiology, School of Public Health, University of Michigan, USA.
⁵ African Population and Health Research Center, Kenya.
⁶ Department of Biostatistics, School of Public Health, University of Michigan, USA.
⁷ Department of Epidemiology, School of Public Health, University of Michigan, USA; Global Institute for Vaccine Equity, University of Michigan, USA; Department of Internal Medicine, Division of Infectious Disease, University of Michigan Medical School, USA.

PMID: 34952757
DOI: 10.1016/j.vaccine.2021.12.017

Abstract

Introduction: Timely receipt of recommended vaccines is a proven strategy to reduce preventable under-five deaths. Kenya has experienced impressive declines in child mortality from 111 to 43 deaths per 1000 live births between 1980 and 2019. However, considerable inequities in timely vaccination remain, which unnecessarily increases risk for serious illness and death. Maternal migration is a potentially important driver of timeliness inequities, as the social and financial stressors of moving to a new community may require a woman to delay her child's immunizations. This analysis examined how maternal migration to informal urban settlements in Nairobi, Kenya influenced childhood vaccination timeliness.

Methods: Data came from the Nairobi Urban Health and Demographic Surveillance System, 2002-2018. Migration exposures were migrant status (migrant, non-migrant), migrant origin (rural, urban), and migrant type (first-time, circular [previously resided in settlement]). Age at vaccine receipt (vaccination timeliness) was calculated for all basic vaccinations. Accelerated failure time models were used to investigate relationships between migration exposures and vaccination timeliness. Confounding was addressed using propensity score weighting.

Results: Over one-third of the children of both migrants and non-migrants received at least one dose late or not at all. Unweighted models showed the children of migrants had shorter time to OPV1 and DPT1 vaccine receipt compared to the children of non-migrants. After accounting for confounding only differences in timeliness for DPT1 remained, with the children of migrants receiving DPT1 significantly earlier than the children of non-migrants. Timeliness was comparable among migrants with rural and urban origins and among first-time and circular migrants.

Conclusion: Although a substantial proportion of children in Nairobi's informal urban settlements do not receive timely vaccination, this analysis found limited evidence that maternal migration and migration characteristics were associated with delays for most doses. Future research should seek to elucidate potential drivers of low vaccination timeliness in Kenya.

Keywords: Informal urban settlements; Kenya; Migration; Propensity score weighting; Slums; Sub-Saharan Africa; Vaccination timeliness.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Child
Child Mortality
Female
Humans
Infant
Kenya / epidemiology
Rural Population*
Transients and Migrants*
Vaccination