A recent global meta-analysis has confirmed the efficacy and safety of TAK-003, also known as Qdenga. This dengue vaccine is now approved in Italy and many other European countries. The study, published in Vaccines, was conducted by researchers from the University of Bologna and the University of Ferrara. It provides the first comprehensive analysis of the vaccine effectiveness in combatting dengue fever. This viral disease affects millions annually and is caused by dengue virus (DENV) types 1 to 4, all of which now co-circulate in many endemic areas.
Qdenga is a live-attenuated dengue vaccine that works by locally replicating in the body and stimulating both humoral and cellular immune responses. It introduces a weakened form of the dengue virus that expresses proteins from all four dengue serotypes. This prompts the immune system to produce antibodies and activate T cells, providing broad protection against dengue. By targeting all four serotypes, Qdenga aims to prevent both primary dengue infection and severe disease from subsequent infections with different serotypes.
The dengue virus poses a significant health risk, infecting around 400 million people yearly, predominantly in warmer regions. The virus is responsible for over 3 million deaths annually, and the situation is exacerbated by climate change, which has expanded the habitat of the mosquito vectors, leading to an increase in dengue outbreaks in new regions, including Europe. Italy has seen a worrying rise in dengue cases, underscoring the urgency of effective preventive measures.
There is currently no specific therapy for dengue fever, and while environmental control efforts to reduce mosquito populations are ongoing, they have not eliminated the risk of outbreaks. Vaccination remains the most promising strategy for preventing the disease. The TAK-003 vaccine, approved in Europe in December 2022, has emerged as a key tool in this effort. However, before this study, a comprehensive assessment of the vaccine’s long-term efficacy and safety had been lacking.
The research team analyzed data from 19 clinical studies involving over 20,000 participants. These studies examined the vaccine effects both one year after a single dose and following the complete vaccination course of two doses. The findings reveal that Qdenga reduces the risk of contracting dengue by over 50% across different age groups, with an impressive safety profile. Notably, more than 90% of those who received both doses of the vaccine developed antibodies against the virus. Even among those who received only a single dose, the immune response was strong: over 70% of adults and more than 90% of children and adolescents developed antibodies. A double-blind, randomized study by Tricou et al. concluded that TAK-003 demonstrated long-term efficacy and safety against all four DENV serotypes in previously exposed individuals and against DENV-1 and DENV-2 in dengue-naive individuals. In the study DEN-301, showed that neutralizing antibodies remained at levels well above those before vaccination for all four dengue serotypes, lasting up to 51 months after the first dose.
The study findings supports the use of the vaccine in preventing dengue, especially in regions where the disease is common. According to the researchers, based on the results related to safety, immunogenicity, and effectiveness, the administration of two doses can be a crucial tool for preventing dengue. The vaccine is considered valuable not only for people living in high-risk areas but also for travelers from regions where dengue is not common, who may be at risk of exposure to the virus.
This research marks a significant milestone in the global fight against dengue fever, offering hope that the disease impact can be significantly reduced through widespread vaccination. The positive outcomes of this study highlight the importance of continued research and global cooperation in addressing the challenges posed by infectious diseases like dengue, especially in the context of a changing climate that is likely to increase the spread of mosquito-borne illnesses.
References
- Flacco ME, Bianconi A, Cioni G, Fiore M, Calò GL, Imperiali G, et al. Immunogenicity, Safety and Efficacy of the Dengue Vaccine TAK-003: A Meta-Analysis. Vaccines. 2024 Jul;12(7):770.
- Tricou V, Yu D, Reynales H, Biswal S, Saez-Llorens X, Sirivichayakul C, et al. Long-term efficacy and safety of a tetravalent dengue vaccine (TAK-003): 4·5-year results from a phase 3, randomised, double-blind, placebo-controlled trial. The Lancet Global Health. 2024 Feb;12(2):e257–70.