Barriers to dengue vaccine coverage in low- and middle-income countries (LMICs)

Dengue is a climate-sensitive infectious disease and the world's fastest-growing vector-borne disease. It disproportionately affects low- and middle-income countries (LMICs), with children most severely affected. Dengvaxia (CYD-TDV) and Qdenga (TAK-003) are the only two licensed dengue vaccines currently available, while Butantan-DV (TV003) is an advanced candidate with promising Phase 3 clinical trial results. Despite the commercial availability of dengue vaccines, coverage remains low in areas with the greatest need. This is driven by technical, social, and geopolitical challenges, as well as growing vaccine hesitancy. There is also an added layer of clinical complexity associated with vaccination against dengue due to the antibody-dependent enhancement (ADE) phenomenon, which can lead to vaccine-enhanced disease. Here, we review the current global landscape of dengue vaccine licensure and coverage, focusing on countries with the highest disease burden. We show that in many countries with a high dengue incidence, dengue vaccines have yet to be licensed, particularly in parts of Africa and South Asia. Even in regions where licensure is more widespread, such as Latin America and Southeast Asia, dengue vaccines are not well integrated into national immunisation programmes and can only be obtained through out-of-pocket payment. We therefore identify several state and market-driven systemic factors, as well as declining vaccine confidence, as barriers to scaling up dengue vaccine access in LMICs. These barriers must be addressed through creative solutions to ensure the equitable distribution of dengue vaccines to the populations and countries that need them the most.