{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,11,7]],"date-time":"2026-11-07T07:22:49Z","timestamp":1794036169518,"version":"4.8.0"},"reference-count":15,"publisher":"Public Library of Science (PLoS)","issue":"2","license":[{"start":{"date-parts":[[2026,2,11]],"date-time":"2026-02-11T00:00:00Z","timestamp":1770768000000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100000865","name":"Bill and Melinda Gates Foundation","doi-asserted-by":"publisher","award":["C1055"],"award-info":[{"award-number":["C1055"]}],"id":[{"id":"10.13039\/100000865","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["www.plosglobalpublichealth.org"],"crossmark-restriction":false},"short-container-title":["PLOS Glob Public Health"],"abstract":"<jats:p>Timeliness of vaccination among children in urban informal settlements is understudied in sub-Saharan Africa. We determined the proportion of children below 5 years who received vaccines on time and the associated factors in two large urban informal settlements in Nairobi, Kenya. We conducted an analytic cross-sectional study in Viwandani and Korogocho, randomly selected households with a child below 5 years, and administered questionnaires to mothers\/caregivers. Timely vaccination was defined according to the Kenya Expanded Programme on Immunization schedule. Vaccination was considered timely if administered within 28 days of birth for Bacille Calmette-Gu\u00e9rin (BCG), between 14 and 18 weeks for Diphtheria-Tetanus-Pertussis-Haemophilus influenzae type b-Hepatitis B dose 3 (DTP-Hib-HepB-3), and between 9 and 10 months for Measles-Containing Vaccine dose 1 (MCV1). Multivariable modified Poisson regression identified the factors associated with timely vaccination. Of 412 children, 216 (52%) with verifiable immunization booklets were analyzed for timeliness. Timely vaccination rates were 90.4% for BCG (189\/209), 90.2% for DTP-HIB-Hep-3 (184\/204), and 84.2% for MCV1 (160\/190). Factors associated with timely vaccination included caregiver uncertainty about access to health services, which reduced the likelihood of timely BCG (adjusted prevalence risk ratio [aPR] 0.87, 95% confidence interval [CI] 0.78-0.96), DTP-Hib-HepB-3 (aPR 0.88, 95% CI 0.79-0.98), and MCV1 (aPR 0.81, 95% CI 0.70-0.94). Compared with Korogocho, children in Viwandani were more likely to receive timely MCV1 (aPR 1.18, 95% CI 1.03-1.35), whereas children of Christian caregivers were less likely than those of non-religious caregivers (aPR 0.83, 95% CI 0.70-0.99). Overall, vaccination timeliness varied by antigen, with a slight decline over time for later-schedule vaccines such as MCV1. Residence, religion, and access to routine health services were key determinants of timely vaccination. Strengthening outreach, faith-based engagement, and reminder systems in informal settlements like Korogocho could enhance vaccine timeliness, particularly for vaccines administered later in infancy.<\/jats:p>","DOI":"10.1371\/journal.pgph.0005462","type":"journal-article","created":{"date-parts":[[2026,2,11]],"date-time":"2026-02-11T18:28:57Z","timestamp":1770834537000},"page":"e0005462","update-policy":"https:\/\/doi.org\/10.1371\/journal.pgph.corrections_policy","source":"Crossref","is-referenced-by-count":1,"title":["Timeliness of vaccine administration among children in urban informal settlements in Nairobi, Kenya"],"prefix":"10.1371","volume":"6","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-2619-562X","authenticated-orcid":true,"given":"Maurine","family":"Ng\u2019oda","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9065-0389","authenticated-orcid":true,"given":"Jonathan","family":"Izudi","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0004-7321-9086","authenticated-orcid":true,"given":"Collins","family":"Omenda","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Anne","family":"Njeri","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Nelson","family":"Mbaya","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Abdhalah","family":"Ziraba","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"340","published-online":{"date-parts":[[2026,2,11]]},"reference":[{"issue":"8","key":"pgph.0005462.ref001","doi-asserted-by":"crossref","first-page":"1900","DOI":"10.1080\/21645515.2019.1708669","article-title":"Why vaccines matter: understanding the broader health, economic, and child development benefits of routine vaccination","volume":"16","author":"A Nandi","year":"2020","journal-title":"Hum Vaccin Immunother"},{"key":"pgph.0005462.ref002","unstructured":"World Health Organization. Vaccines and immunization. https:\/\/www.who.int\/health-topics\/vaccines-and-immunization#tab=tab_1. 2024."},{"key":"pgph.0005462.ref003","doi-asserted-by":"crossref","unstructured":"Bullen M, Heriot GS, Jamrozik E. Herd immunity, vaccination and moral obligation. 2023;2:636\u201341.","DOI":"10.1136\/jme-2022-108485"},{"issue":"1","key":"pgph.0005462.ref004","doi-asserted-by":"crossref","first-page":"2295977","DOI":"10.1080\/21645515.2023.2295977","article-title":"The urban-poor vaccination: Challenges and strategies in low-and-middle income countries","volume":"20","author":"B Zimba","year":"2024","journal-title":"Hum Vaccin Immunother"},{"key":"pgph.0005462.ref005","doi-asserted-by":"crossref","unstructured":"Park JE, Kibe P, Yeboah G, Oyebode O, Harris B, Ajisola MM. Factors associated with accessing and utilisation of healthcare and provision of health services for residents of slums in low and middle- income countries: a scoping review of recent literature. 2022;1\u201318.","DOI":"10.1136\/bmjopen-2021-055415"},{"key":"pgph.0005462.ref006","volume-title":"Demographic and Health Survey 2022","author":"KNBS","year":"2023"},{"key":"pgph.0005462.ref007","unstructured":"UNICEF. 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