In Utero Exposure to Chikungunya and Child Morbimortality: A Population-Based Longitudinal Study

Background: Chikungunya is a growing public health threat linked to climate change. Vertical transmission is reported, but the long-term effect of in-utero Chikungunya exposure is not known. Methods: This was a matched cohort study of children born between 2015 to 2018 and registered at CIDACS Birth Cohort. Exposure was in-utero Chikungunya infection. Outcomes were all-cause first hospitalization and death. Ten controls were matched for case, and were followed until outcome, third birthday, or study end. Adjusted stratified Cox models were used to obtain hazard ratio. Findings: A total of 3,154 exposed children and 31,540 unexposed children were included. During follow-up, 687 (21%) exposed and 5,705 (18%) unexposed experienced hospitalization. In-utero Chikungunya was associated with a 22% increase in the hazard of hospitalization (95% CI: 1.12–1.32. The risk was twofold higher among those exposed to intrapartum infection (HR: 1.98, 95% CI: 1.40–2.71). Elevated hospitalization hazards were also observed following exposure during the first and second trimesters. Death risk was elevated in the intrapartum-exposed group, but the interval estimate was unstable. Interpretation: We observed increased risk of hospitalization and death among infants with in-utero Chikungunya exposure.