Modelling the relative contribution of infection, routine vaccination and supplementary immunisation activities to measles seroconversion in Kenyan Children
Mburu, Caroline Ojal, John Selim, Rose Ombati, Rose Akech, Donald Karia, Boniface Tuju, James Sigilai, Antipa Smits, Gaby van Gageldonk, Pieter
Mburu, Caroline
Ojal, John
Selim, Rose
Ombati, Rose
Akech, Donald
Karia, Boniface
Tuju, James
Sigilai, Antipa
Smits, Gaby
van Gageldonk, Pieter
Series / Report no.
Open Access
Type
Journal Article
Article
Article
Language
en
Date
2025-09-22
Research Projects
Organizational Units
Journal Issue
Title
Modelling the relative contribution of infection, routine vaccination and supplementary immunisation activities to measles seroconversion in Kenyan Children
Translated Title
Published in
PLoS Comput Biol 2025; 21(9):e1013531
Abstract
BACKGROUND: Measles outbreaks continue to cause a large burden of disease in Africa including Kenya. We used information from regular serological surveys in Kilifi Health and Demographic Surveillance System (KHDSS) in combination with mathematical modelling to estimate the relative contribution of the vaccination programme to current measles immunity.
METHODS: We developed a static birth cohort model to track the proportion of children who are either measles naïve or seroconverted due to natural infection or vaccination through first dose of measles-containing vaccine (MCV1), the second dose (MCV2), or supplementary immunisation activities (SIAs). We fitted the model to biennial paediatric serological survey and case notification data and used vaccination coverage estimates from the KHDSS to estimate the relative contributions of vaccination and infection to measles immunity in Kilifi.
RESULTS: We estimated that between 2009 and 2021, 60% (95%CI 55-64%) of measles seroconversion in Kilifi was attributable to MCV1, with MCV2 contributing 1.0% (95%CI 0.9-1.1%) since its introduction. Natural infection and SIAs accounted for 24% (95%CI 17-31%) and 16% (95%CI 14-19%), respectively. A hypothetical 10% increase in MCV1 coverage increased the seroconversion attributed to MCV1 to 67% (95%CI 63-71%), with concurrent reductions in seroconversion from natural infection and SIAs to 13% (95%CI 9-18%) and 10% (95%CI 9-12%), respectively. Importantly, this same 10% increase in MCV1, if administered promptly at 9 months, could potentially reduce seroconversion from natural infection further from 24% to 11% (95%CI 07-15%) and reliance on SIAs from 16% to 8% (95% CI 7-10%).
CONCLUSION: Optimizing routine coverage timing and uptake is crucial for reducing SIAs dependence and measles susceptibility. A 10% MCV1 coverage increase could have halved susceptibility and lessened SIA demand, highlighting the potential of minor improvements in coverage to alleviate measles and reduce costly SIAs.