CONVICTION-CHIK study on the effect of convalescent plasma for mother-to-child Chikungunya infection: protocol for a multicentre, open label, single-arm, phase II trial

BACKGROUND: Mother-to-child peripartum transmission of Chikungunya infection may induce severe illness with neonatal encephalitis/encephalopathy, leading to major neurological sequalae in offspring. There is not, at present, any licensed vaccine or treatment for Chikungunya virus (CHIKV) disease in pregnant women or neonates. However, there are a range of potential treatments, including passive immune therapies by hyperimmune antibodies or blood products, which warrant further investigation. Our study aims to determine whether the early administration of CHIKV convalescent plasma donor is effective in preventing several adverse outcomes in neonates exposed to maternal peripartum CHIKV infection. METHODS: CONVICTION-CHIK is a multicentre, interventional, phase II, single-arm trial, that will be conducted in two French overseas departments in the Indian Ocean throughout 2026. Neonates with the following criteria will be included: (1) mother with a clinical and/or biological diagnosis of CHIKV infection occurring between day -2 and + 2 around delivery; (2) cared for in a 3rd level neonatal intensive care unit; (3) treatment administration possible within 12 h from diagnosis of maternal infection. The intervention consists in the transfusion of 25 mL/kg of ABO CHIKV convalescent plasma over 4 h. The primary endpoint is the proportion of newborn infants treated with CHIKV convalescent plasma who survive without encephalitis/encephalopathy in the first 5 days of life. This outcome will also be assessed in a parallel cohort of untreated newborn infants exposed to peripartum CHIKV infection. Secondary endpoints are clinical, biological, and brain imaging findings of neonatal CHIKV infection, in treated and untreated neonates. Based on an expected decrease in the primary endpoint from 25% to 3% in the intervention group, the required sample size is 30 treated neonates. A parallel cohort of 30 contemporaneous untreated neonates will be enrolled to provide exploratory context for the observed treatment effect. DISCUSSION: If successful, this research will expand the therapeutic arsenal for treating peripartum neonatal CHIKV infection, in addition to symptomatic management of organ failure. The results of this study will allow to consider the feasibility to implement the systematic collection of convalescent plasma following Chikungunya outbreaks, for the management of subsequent epidemics. TRIAL REGISTRATION: NCT07190560 (registered 17 September 2025).