What is Dengvaxia?
Dengvaxia is a vaccine developed to protect against
dengue virus infection, a significant public health challenge, particularly in tropical and subtropical regions. The vaccine was created by Sanofi Pasteur and is known scientifically as CYD-TDV. It is designed to prevent infection from all four serotypes of the dengue virus.
How Does Dengvaxia Work?
Dengvaxia is a live attenuated viral vaccine, meaning it uses a weakened form of the virus to stimulate the immune system without causing the disease itself. The vaccine is structured to mimic the natural infection process, prompting the immune system to produce antibodies against the dengue virus. This prepares the body to fight off future infections by any of the four dengue virus serotypes.
Who Can Benefit from Dengvaxia?
The vaccine is recommended for individuals aged 9 through 45 who live in endemic areas and have had a prior confirmed
dengue infection. It is crucial for the vaccinee to have been previously infected because Dengvaxia has been shown to be most effective and safest in those who have already been exposed to the virus.
Why is Prior Infection Important?
Studies have shown that individuals who receive the vaccine without prior dengue infection may have an increased risk of severe dengue disease if they get infected after vaccination. This is due to a phenomenon known as
antibody-dependent enhancement (ADE), where suboptimal antibodies enhance the virus's ability to infect host cells, leading to more severe disease.
What is the Controversy Surrounding Dengvaxia?
The controversy primarily stems from the initial lack of clarity regarding the vaccine's safety in seronegative individuals. When first introduced, it was administered broadly without requiring prior infection confirmation. This resulted in adverse outcomes in some cases, leading to public fear and hesitancy. Subsequent revelations about increased risks for those without prior dengue exposure prompted updates in vaccination guidelines and raised concerns about the
safety profile and ethical considerations of vaccine deployment.
What are the Current Recommendations?
Current guidelines recommend the use of Dengvaxia only in those who have had laboratory-confirmed prior dengue infection. It is administered as a series of three injections, with the doses given six months apart. The
World Health Organization and other health authorities emphasize the importance of targeted vaccination strategies to ensure that only eligible individuals receive the vaccine.
What are the Future Prospects of Dengvaxia?
Despite the initial setbacks, Dengvaxia remains an essential tool in the fight against dengue in endemic regions, where it can significantly reduce the burden of disease. Ongoing research and monitoring are crucial to better understand the long-term effects and optimize vaccination strategies. Additionally, the development of new dengue vaccines continues, with the hope of creating formulations that are safe and effective for a broader population, including those without prior infection.
Conclusion
Dengvaxia represents a significant advancement in infectious disease control, offering protection against one of the world's most pervasive mosquito-borne illnesses. However, its use is best suited to specific populations, underscoring the need for careful screening and vaccination policies. As research progresses, the lessons learned from Dengvaxia's deployment will be invaluable in guiding the future development and implementation of vaccines for
infectious diseases.
