Chikungunya Virus Infection

In the context of the ongoing chikungunya epidemic in Réunion Island and the anticipated epidemic in French Guiana, the investigators propose an ambispective study to evaluate the real-world effectiveness, safety, and immunogenicity of the recommended vaccines, IXCHIQ® and VIMKUNYA®, as defined by the French National Authority for Health (HAS).

The goal of this clinical trial is to learn if administration of plasma, from a whole blood donation from an individual who has declared a Chikungunya infection for less than 6 months , to a newborn, whose mother has a peripartum chikungunya infection, will have an impact on the proportion of newborns surviving without encephalitis/encephalopathy (EE) within the first 5 days of life. Researchers will compare results to an observational study of 30 newborns who couldn't have been proposed to participate at the clinical trial, because of delay of diagnosis or delay of transfer to hospital which doesn't allow transfusion or parents not accepting plasma transfusion to the newborn. Participants of the clinical trial will: * receive a transfusion, * visit the clinic and undergo biological tests every day until day 7 and once between 1 and 3 months. Participant of observational study as part of their regular medical care, and biological data will be reused for the research from the mother's diagnosis until the newborn reaches 3 months of age

This is a Phase I, randomized, single-blind, placebo-controlled, study of four separate dose cohorts, with a 42-day interval between each vaccine dose, of a novel Chikungunya Peptide Immunotherapy Vaccine in Healthy Adults (18-60 years of age). All participants will undergo a screening visit scheduled for a maximum of 28 days before the enrolment in the clinical study and will provide a blood sample for clinical laboratory tests (complete blood count (CBC)\*, platelet count, alanine aminotransferase (ALT), aspartate aminotransferase (AST), total bilirubin, serum creatinine and activated partial thromboplastin time (aPTT), human immunodeficiency virus (HIV), hepatitis B virus (HBV), hepatitis C virus (HCV)), and a urine sample for tests for Urinary protein, Urinary blood, Urinary glucose and human chorionic gonadotropin β-subunit (βhCG) urine test (only the female participants)) in order to confirm their eligibility for participation in the study. A total of 40 participants are planned to be enrolled. A randomization system will be used to assign treatment group and participant number at the clinical site. Participants will receive 2 injections, 42 days apart. A final visit will take place at Day 407 (i.e. 365 days after last vaccination). Participants will be kept under observation for a minimum of one hour after each vaccination to ensure their safety. Reactogenicity data will be collected in all participants after each vaccine injection: solicited injection site reactions will be collected for Days 0-10 and Days 42-52 and solicited systemic reactions will be collected for Days 0-21 and Days 42-63. Unsolicited events will be collected for Days 0-52. Serious adverse events (SAEs) will be reported throughout the study (from inclusion until 12 months after last vaccination). Serious and non-serious medically attended adverse events (MAAEs) and adverse events of special interest (AESIs) will be collected throughout the study (from inclusion until 12 months after last vaccination).

Chikungunya is an arboviral disease transmitted by Aedes mosquitoes, present in intertropical zones and Europe. In August 2024, autochthonous cases appeared on Réunion, followed by a large epidemic. In March 2025, the incidence surpassed 2,000 cases per week. Due to a lack of data, the Haut Comité de Santé Publique issued an unfavorable opinion on using substances of human origin during the epidemic. Although the presence of Chikungunya virus genome in semen has been reported in 7 men, the incidence of viral excretion is unknown. This raises concerns about the risk of sexual transmission and infectivity, especially in assisted reproductive technologies. Previous studies on other arboviruses (Zika, dengue) have explored genital excretion. The goal of this prospective pilot study is to investigate Chikungunya virus presence and infectivity in semen, as well as to evaluate the effectiveness of sperm preparation methods in obtaining virus-free gametes. Fifteen patients with acute Chikungunya virus infection will provide blood, urine, and semen samples at different time points (7, 15, 30, 60, 90, and 180 days post-symptom onset). Seminal plasma, native sperm cells, and prepared sperm fractions will be tested for Chikungunya virus RNA at the University Hospital of La Réunion and Toulouse. This study will provide insights into viral excretion patterns and help improve the safety of medically assisted reproduction in epidemic situations.

Zoonoses and arboviroses refer to a group of diseases transmitted from animals to humans, either directly or indirectly (via mosquitoes, ticks or contact with contaminated environments). Most of these diseases are found in certain tropical zones, but global warming and increased international trade are modifying their geographical distribution, with a gradual trend towards temperate regions. A number of these pathogens have already been detected in Occitania, including dengue fever, West Nile, leishmaniasis and Q fever. Given the region's high mosquito population and favorable climatic conditions, other zoonoses have a strong potential to appear in the region, or may already be circulating at a low level. The study focuses on 18 pathogens selected for their potential to emerge and establish themselves in the Occitanie region: Leishmaniasis, Leptospirosis, Brucellosis, Q fever, Rickettsiosis, Tularemia, Psittacosis, Lyme disease, Tick-borne encephalitis, Hantavirus, Hepatitis E virus, Dengue virus, Zika virus, Chikungunya virus, West-Nile virus, Usutu virus, Toscana virus, Crimean-Congo haemorrhagic fever virus. The aim of the study is to find out whether patients have antibodies against these infectious agents, which would indicate that they have been exposed to them in the past, even in the absence of symptoms. Describing the circulation of these pathogens will enable to implement appropriate public health measures to avoid the risk of epidemics (mosquito control, informing professionals, etc.), as well as to assess the risk incurred in the workplace and have this risk recognized by the healthcare system.