Dengue is a viral disease transmitted by the Aedes aegypti mosquito, prevalent in tropical and subtropical regions of the world. It represents a significant public health challenge, with millions of cases annually and thousands of deaths. The Qdenga vaccine appears as a promising innovation in the fight against this disease.
The vaccine Qdenga, developed by Takeda Pharmaceutical Company, was approved by the National Health Surveillance Agency (Anvisa) in Brazil in March 2023. The approval marked a significant advance in the prevention of dengue in the country, allowing the vaccination of a broad public against the disease.Everything about the new Qdenga vaccine here
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Who Can Get Vaccinated with Qdenga?
Anvisa approves the Qdenga vaccine for individuals aged 4 to 60 years, as there is insufficient data on its effectiveness in people over 60 years of age. The vaccine is recommended for both those who have already had dengue fever and those who have never been infected, being the first vaccine released in Brazil for people with no history of contact with the virus.
However, Qdenga should not be administered to people allergic to its components, individuals with compromised immune systems or immunosuppressive conditions, as well as pregnant and lactating women, due to the lack of conclusive studies on safety in these groups.
Qdenga Vaccine Side Effects
Clinical studies of the Qdenga vaccine have indicated that adverse reactions may occur, generally within two days of administration. These reactions were typically mild to moderate and lasted 1 to 3 days.
Attention: These reactions do not contraindicate the use of the vaccine when applied to the correct population.
Most Common Reactions
The most frequently reported adverse reactions were:
- Pain at the injection site: 50%
- Headache: 35%
- Muscle pain: 31%
- Redness at the injection site: 27%
- Malaise: 24%
- Weakness: 20%
- Fever: 11%
Comments
- Adverse reactions tend to be less frequent after administration of the second dose of Qdenga.
Global Impact
Currently, dengue is endemic in more than 100 countries. The World Health Organization (WHO) estimates that up to 400 million people are infected annually. The disease ranges from a mild fever to severe forms, such as dengue hemorrhagic fever and dengue shock syndrome, which can be fatal.
Development of the Qdenga Vaccine
Given the wide spread and impact of dengue fever, the need for an effective vaccine is clear. Until recently, control efforts focused primarily on reducing mosquito vectors and raising public awareness. However, these methods have their limitations, and an effective vaccine offers a more robust preventive solution.
How will the vaccine be distributed?
According to the Ministry of Health, doses of the vaccine from the donated batch will be destined for municipalities with more than 100 thousand inhabitants with high transmission of the disease in the last ten years, also taking into account high rates in recent months.
The Creation of Qdenga
Qdenga, developed by Takeda Pharmaceutical Company, is a tetravalent vaccine, that is, it aims to protect against the four serotypes of the dengue virus (DENV 1, 2, 3 and 4). The development of the vaccine involved years of research and rigorous clinical trials.
Research and Development
Qdenga's development began with preclinical studies that demonstrated its effectiveness in animal models. Subsequent clinical trials were carried out in several phases:
- Phase 1: Evaluated the safety and immunogenicity of the vaccine in small groups of volunteers.
- Level 2: Testing on a larger group to determine optimal dosage and continue evaluating safety.
- Phase 3: Large-scale trials to evaluate efficacy and safety in different populations and ages.
The results of these studies were promising, showing that Qdenga can induce a robust immune response against all four dengue virus serotypes.
How does Qdenga work?
Qdenga is a live attenuated vaccine. This means it contains weakened dengue viruses that do not cause the disease, but stimulate the immune system to produce a defensive response. When a vaccinated person is exposed to the dengue virus, their immune system can respond quickly to neutralize the virus.
Immune Response
The immunological response to Qdenga involves the production of neutralizing antibodies against the four serotypes of the dengue virus. These antibodies help prevent infection and reduce the severity of the disease if an infection occurs.
Effectiveness of Qdenga
Qdenga's phase 3 clinical trials, known as TIDES (Trial to Evaluate Efficacy and Safety of a Dengue Vaccine), were carried out in several dengue endemic countries. The results showed an overall efficacy of approximately 80% in preventing symptomatic dengue. Efficacy varied slightly between serotypes, but the vaccine offered substantial protection against all of them.
Long Term Protection
In addition to initial efficacy, follow-up studies indicate that Qdenga offers long-lasting protection. Trial participants continued to be monitored for several years to assess the duration of immunity, and the results suggest continued protection.
Vaccine Safety
Safety is a crucial consideration in the development of any vaccine. Qdenga underwent extensive safety evaluation during its clinical trials. The most common side effects were mild and included pain at the injection site, fever and fatigue. There were no significant reports of serious adverse effects related to the vaccine.
Post-Market Evaluations
Following regulatory approval, Qdenga continues to be monitored through post-market surveillance systems. These systems help identify any rare adverse effects that may have been missed in clinical trials. To date, post-marketing safety data has been consistent with clinical trial results.
Impact on Public Health
The introduction of Qdenga has the potential to significantly reduce the global burden of dengue. With an effective vaccine, a decrease in infections, hospitalizations and deaths associated with the disease is expected. This would ease pressure on healthcare systems, especially in endemic countries.
Economic Benefits
In addition to the health benefits, reducing dengue fever also has economic implications. Dengue is responsible for substantial costs due to medical treatment, lost productivity, and vector control efforts. Mass vaccination could reduce these costs and improve the quality of life of affected populations.
Immunization Programs
Effective implementation of Qdenga requires well-planned vaccination strategies. Immunization programs must be developed in collaboration with public health authorities, considering factors such as population coverage, distribution logistics and awareness campaigns.
Challenges and Final Considerations
One of the main challenges in implementing Qdenga is ensuring equitable access to the vaccine. Low- and middle-income countries, where dengue is more prevalent, may face difficulties in financing and distributing the vaccine. International initiatives and public-private partnerships will be essential to overcome these obstacles.
Viral Resistance
Another aspect to be monitored is the possibility of viral resistance. Although Qdenga has shown efficacy against all four serotypes, the evolution of the virus is a concern. Continued surveillance and research are needed to identify and respond to any changes in vaccine effectiveness.
Public Acceptance
Public acceptance of the vaccine is also crucial. Education and awareness campaigns should address concerns and myths about vaccination, promoting confidence in Qdenga and increasing coverage rates.
Conclusion
The Qdenga vaccine represents a significant advance in the fight against dengue. With robust efficacy and a positive safety profile, it offers a powerful tool to reduce the global burden of disease. However, successful vaccine rollout will depend on coordinated efforts to ensure equitable access, monitor viral resistance, and promote public acceptance. As we move forward, Qdenga has the potential to transform the global approach to dengue prevention, saving lives and improving public health around the world.
