The public authorities have established a strengthened system for epidemiological surveillance, early warning, operational response, and community outreach in Réunion and Mayotte, under the leadership of the Indian Ocean Regional Health Agency. Thus, in Réunion in 2016, as part of the plan to combat mosquito-borne diseases, the specific response mechanism for the spread of dengue—which included the mobilization of public authorities, professionals, field workers, and the general public—helped prevent the situation from escalating into a major epidemic. The intervention plan most often combines investigation, active case finding, distribution of supplies, logistical support for treatment, dissemination of prevention messages, and community mobilization. The challenge is certainly to raise public awareness and alert the public to emerging risks, but also to rely on the mobilization of the population. In this regard, engaging community organizations for social mobilization has proven effective in reinforcing prevention habits within communities.