Dengue fever, a mosquito-borne viral infection, imposes a substantial public health challenge worldwide. The global burden of dengue has been gradually increasing, with millions of cases reported per annum. In the quest to fight dengue fever, scientists and researchers are continually striving to develop innovative vaccines that can provide effective protection against all four dengue virus serotypes [1].
This blog explores the promise of a new generation of dengue vaccines and their potential to reshape the landscape of dengue prevention.
Understanding dengue fever
Before delving into the new generation of dengue vaccines, it is important to discuss the complexities of the disease. Dengue is a viral infection resulting from the dengue virus (DENV), which has four distinct serotypes (DENV-1 to DENV-4).
Presently, approximately half of the global population is vulnerable to dengue, leading to an estimated 100–400 million infections annually. The prevalence of dengue is observed in tropical and sub-tropical climates across the globe, predominantly in urban and semi-urban regions [1,2].
The challenges of traditional vaccine approaches
Developing a vaccine for dengue has proven to be a difficult task due to the exceptional challenges posed by the multiple serotypes of the virus. Early attempts at vaccine development saw obstructions, including the risk of aggravating the severity of the disease in individuals with prior exposure to one serotype. These challenges encouraged researchers to explore alternative strategies to develop a safe and effective dengue vaccine [1,2].
The dawn of a new generation: Promising data, cautious optimism
Recent years have witnessed the emergence of a new generation of dengue vaccines, representing a paradigm shift in the approach to dengue prevention. Two promising candidates have shown encouraging results in recent clinical trials, which comprises:
TAK-003 and
Butantan-DV
These live-attenuated vaccines have demonstrated significant efficacy against severe dengue and offer protection against multiple serotypes. Since these vaccines have now finished phase III efficacy trials, cautious optimism is warranted again.
Takeda Pharmaceutical has recently secured approval from Indonesian, European Commission, and Brazilian regulatory authorities for the use of their two-dose vaccine (TAK-003) in individuals aged 4 years and older, irrespective of their baseline dengue immune status.
Additionally, the Instituto Butantan, U.S. NIH, and Merck (MSD) have shared initial findings from a phase III trial and notably, after two years of surveillance, there was the absence of severe dengue cases instances with clinical warning signs. Thus, these new vaccines represent a paradigm shift in dengue vaccine development [1].
Tangible benefits
While the pursuit of a perfect dengue vaccine continues, the new generation offers tangible benefits which are stated below.
These new-generation vaccines are designed to elicit a balanced immune response against all four dengue serotypes, potentially mitigating the risk of antibody-dependent enhancement (ADE). ADE is a phenomenon where pre-existing immunity to one serotype can worsen disease severity upon infection with another serotype.
Additionally, these vaccines demonstrated remarkably high efficacy against severe forms of dengue and also in individuals previously infected with the virus, highlighting its potential to protect a wider population.
These vaccines are highly effective in preventing hospitalization, severe complications, and even death, providing a crucial layer of protection for vulnerable populations.
Even with certain limitations, these vaccines have the potential to significantly reduce the burden of dengue, especially in areas with high disease prevalence [1].
Beyond efficacy: Addressing global challenges
While the new generation of dengue vaccines presents exciting possibilities for disease control, their success extends beyond mere efficacy. Ensuring affordability and equitable access, particularly in developing nations where the burden of dengue is highest, is critical. Additionally, fostering public trust and addressing vaccine hesitancy through transparent communication and robust surveillance systems are crucial for achieving widespread adoption and maximizing impact [1].
Looking ahead: Continued innovation and collaboration
The development of the new dengue vaccines marks a significant milestone in the fight against this disease. However, the journey is far from over. Continued research and development are essential to improve vaccine efficacy, address enduring challenges, and explore alternative vaccine platforms. By working hand-in-hand, scientists, healthcare providers, and policymakers can overcome challenges and accelerate the successful deployment of these vaccines, saving countless lives.
References
1. Thomas, S.J. 'Is new dengue vaccine efficacy data a relief or cause for concern?'. npj Vaccines. (2023) 8(1), 1–6. DOI: 10.1038/s41541-023-00658-2.
2. Dengue and severe dengue' [https://www.who.int/news-room/fact-sheets/detail/dengue-and-severe-dengue].
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