Abstract
Chikungunya exposure in-utero is linked to neonatal morbidity and neurodevelopmental effects. We examined the long-term morbidity associated with in-utero Chikungunya. This registry-based cohort study linked records of infants born in Brazil between 2015 and 2018, with all-cause first hospitalization and death as outcome. Infants were followed until the outcome, their third birthday, or the end of the study. Adjusted stratified Cox models were used to estimate hazard ratios (HR), 95% confidence intervals (95% CIs), and absolute risk differences. A total of 1,821 exposed and 18,210 unexposed infants were included. The HR for hospitalization was 1.21 (95% CI: 1.11–1.36), corresponding to 37 excess hospitalizations per 1000 exposed (95% CI: 16-64). The risk was twofold for intrapartum exposure (HR 2.08, 95% CI: 1.33–3.44) and elevated for first- and second-trimester exposure. Evidence for risk of death was limited. Here we show an elevated hospitalization risk associated with in-utero Chikungunya exposure.
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Data availability
The relevant data are included in the manuscript and appendix. Deidentified individual participant data are available on reasonable request to CIDACS, subject to institutional collaboration agreements and Brazilian ethics committee approval.
Code availability
No custom code was developed; analysis was conducted using publicly available R packages. Code is available upon request.
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Acknowledgments
EP receives funding from Wellcome Trust 225925/Z/22/Z. TC-S receives funding from the Royal Society (NIF¥R1¥231435).
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M.K. and E.P. conceived and designed the study and developed the protocol. M.K., O.C., and T.C.-S. performed the data analysis. M.K. drafted the manuscript. M.K., O.C., T.C.-S., V.B., M.G.T., M.B., and E.P. contributed to the interpretation of data and critically reviewed and approved the final version of the manuscript. E.P. supervised the study. M.K., O.C., T.C.-S., and E.P. had full access to all the data and took responsibility for the integrity of the data and the accuracy of the data analysis.
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Kushibuchi, M., Carroll, O., Cerqueira-Silva, T. et al. In-utero exposure to chikungunya and child morbimortality: a population-based study using linked routine data. Nat Commun (2026). https://doi.org/10.1038/s41467-026-70786-5
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DOI: https://doi.org/10.1038/s41467-026-70786-5
