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. 2025 Jun 10;113(2):338-343.
doi: 10.4269/ajtmh.24-0737. Print 2025 Aug 6.

Completion of Multidose COVID-19 Vaccination Among Adolescents and Adults in Urban Informal Settlements in Nairobi, Kenya

Maurine Ng'oda  1 , Jonathan Izudi  2   3 , Collins Otieno  1 , Daniel Mwanga  2 , Richard E Sanya  1 , Abdhalah Ziraba  1
Affiliations

Completion of Multidose COVID-19 Vaccination Among Adolescents and Adults in Urban Informal Settlements in Nairobi, Kenya

Maurine Ng'oda et al. Am J Trop Med Hyg. .

Abstract

Completion of vaccine doses is essential for robust immunity and long-term protection against specific diseases. This study aimed to investigate factors associated with the completion of multidose coronavirus disease 2019 (COVID-19) vaccines (MDVs) among adolescents and adults in two informal urban settlements in Nairobi, Kenya. We analyzed data from the Kenya Multisite Integrated Serosurveillance project. We defined completion of MDV as receiving an additional COVID-19 vaccine dose between weeks 6 and 8 after the first COVID-19 vaccination shot. We applied the modified Poisson regression model with robust standard errors to determine the factors that were independently associated with the completion of MDV. We analyzed data from 402 individuals aged 14-90 years and found that the completion rate for MDV was 85.3%. In the adjusted analysis, participants aged ≥60 years (adjusted prevalence risk ratio [aPR] 1.30, 95% CI 1.05-1.60) and those who recommended the COVID-19 vaccine to others (aPR 1.40, 95% CI 1.00-1.96) were significantly more likely to complete MDV. Individuals aged 25-59 years (aPR 1.22, 95% CI 0.99-1.50), those who perceived themselves as being at risk for COVID-19 (aPR 1.09, 95% CI 0.99-1.19), and those who had access to healthcare during the pandemic tended to have a higher completion of MDV. Overall, the MDV completion rate is relatively high; however, public health interventions should endeavor to target those being left behind such as younger individuals and those hesitant about vaccination.

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Conflict of interest statement

Disclosures: The KEMIS project obtained ethical approval from the Kenya Medical Research Institute Scientific and Ethics Review Unit (Reference no. KEMRI/SERU/CGMR-C/203/4085), the National Commission for Science, Technology, and Innovation (License no. NACOSTI/P/21/13771), the Oxford Tropical Research Ethics Committee (Reference no. 44–20), and the London School of Hygiene and Tropical Medicine Research Ethics Committee (Reference no. 26950). Written parental/guardian consent was obtained for participants aged <18 years, accompanied by written assent for children aged 13–17 years. Authors declare no competing interests.

Figures

Figure 1.
Figure 1.
Study profile based on eligibility criteria.
See this image and copyright information in PMC

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