Dengue is a mosquito-borne viral disease affecting millions across Asia, Africa, and Latin America, with its geographic range expanding due to warmer temperatures and urban growth that support mosquito populations. Despite being caused by a virus and triggering immune responses like other vaccine-preventable diseases, dengue presents unique challenges because it has four closely related serotypes. Infection with one serotype protects against that type but not the others, and previous infection can sometimes make subsequent infections more severe. Around 390 million infections occur globally each year, making dengue a major public health concern in Africa and beyond.
Currently, Dengvaxia is the only widely used dengue vaccine, but it is recommended only for individuals previously infected with the virus. The WHO has also recommended TAK-003 for children aged 6–16 in high-transmission settings, regardless of prior infection. Next-generation vaccines are under development, including in Brazil, aiming to improve immune protection across all four serotypes. Research emphasizes that vaccines must generate a balanced immune response; incomplete protection can increase the risk of severe disease in some individuals. Vaccine effectiveness varies depending on prior infection, age, and transmission intensity, necessitating context-specific strategies.
Dengue outbreaks have been documented in several African countries, including Kenya, Tanzania, Sudan, Senegal, and Côte d’Ivoire, and the disease may be more widespread than recognized due to underdeveloped surveillance systems. Aedes aegypti mosquitoes, which breed in standing water near human settlements, transmit the virus. Symptoms include high fever, headaches, eye pain, muscle and joint pain, nausea, and rash. Severe infections can lead to bleeding, organ damage, or shock. Urbanization, travel, and climate change have contributed to rising dengue cases in recent decades.
A key challenge in vaccine development is antibody-dependent enhancement, where antibodies from a previous infection may worsen subsequent infections. Vaccine performance is influenced by prior exposure to dengue, the quality of antibodies produced, age, and local transmission levels. Vaccines perform best in individuals with prior exposure, while those never infected may experience weaker protection or increased hospitalization risk. Research shows that strong, neutralizing antibodies are crucial for protection, while weak antibodies may contribute to severe disease.
Dengue vaccination strategies must be tailored to epidemiological conditions. In high-transmission regions, vaccines can provide substantial benefits, whereas in low-transmission areas, pre-vaccination screening may be necessary. Long-term safety monitoring is critical, as effects may emerge only after natural infections occur. Transparent communication is essential to maintain public trust, especially given past controversies such as those surrounding Dengvaxia in the Philippines. Continued research investment is necessary to understand complex immune responses and develop effective vaccines.
The lessons from dengue extend beyond the disease itself. As mosquito-borne illnesses spread due to environmental change, understanding how to design vaccines for biologically complex pathogens becomes increasingly important. Effective vaccination strategies, combined with robust surveillance and clear public communication, are central to controlling dengue and mitigating its growing global impact.
