Dengue Vaccine Strategy in Children Aged 9 to 17 Years in the French Caribbean

Overview

Dengue fever, an arbovirus transmitted by the Aedes mosquito, is a public health problem in all tropical and subtropical regions of the world. There is currently no antiviral treatment and vector control has shown its limits. The 2018 European marketing authorization of the tetravalent chimeric yellow fever / dengue vaccine (Dengvaxia®) is a major step forward in the fight against the disease. Dengvaxia® is indicated for the prevention of dengue due to serotypes DENV 1-4 in subjects aged 9 to 45 years with a history of infection with the dengue virus and living in endemic areas (seroprevalence of at least 70% in the target population). Dengue seroprevalence data in the French Caribbean territories of Martinique and Guadeloupe dates back to 2011 and concerns only adult blood donors aged 18 to 70 years. To date, no data exists for individuals aged 9 to 17 years in the region. In order to implement an optimal vaccine introduction strategy for these territories, the main aim of the DengueSEA study is to estimate the seroprevalence of the Dengue viruses (DENV 1-4) in 9-17 year olds giving a blood sample as part of care in hospital departments of the French Caribbean islands of Martinique and Guadeloupe.

The Dengvaxia® vaccine is being implemented in a difficult context: complex administration of the vaccine with the need to perform a biological test beforehand and to administer 3 vaccine doses, inconsistent efficacy, controversies and legal actions against the manufacturer in some countries where the vaccine has been used in children under 9 years of age, and general mistrust of vaccines, particularly the most recent ones. In Martinique and Guadeloupe, where dengue circulates in an endo-epidemic mode, outbreaks involving all four DENV serotypes were observed in 1997, 2001, 2005, 2007, 2010 and 2013. Dengue seroprevalence for the region, estimated in 18-70 year old adult blood donors in 2011, was 93.5% (95% CI \[91.5-95.1\]). It was 86.7% (95% CI \[69.3-96.2\]) in 18- to 19-year-olds. A single dengue virus infection (primary dengue) was observed in 3% of dengue-positive donors. The remainder had been infected with two or more dengue viruses. To date, no such seroprevalence data exists for individuals aged 9 to 17 years in these regions, hence the DengueSEA study. At the same time, a survey on the acceptability of dengue vaccination, conducted among parents/legal guardians of participating children/adolescents will allow the assessment of the degree of vaccine hesitancy, particularly for Dengvaxia®, and to identify its main determinants. In addition, Martinique and Guadeloupe were affected in 2016 by an epidemic of the Zika virus infection, which affected 50 to 60% of the population. The antigenic relationship between dengue and Zika viruses can be the cause of serological cross-reactions and could have an impact on the efficacy and tolerance of dengue vaccines in individuals with a history of Zika virus infection. This justifies the conduct of a joint seroprevalence study of Zika and dengue virus infections in the study population. The DengueSEA study is a key towards the implementation of an optimal dengue vaccination strategy for children aged 9 to 17 years in the French Caribbean. The results of this research will also permit better organization of health care services and better management of medical resources, particularly in anticipation of future dengue epidemics in the region. Potential vaccine acceptability challenges will also be better anticipated. Finally, the constitution of a biological collection will allow the evaluation of future serological tests developed to select eligible individuals for dengue vaccination, notably with Dengvaxia®, and to carry out further seroprevalence studies on arboviruses.