Dengue fever 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 and thousands of deaths each year. The Qdenga vaccine emerges 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 fever in the country, allowing the vaccination of a wide public against the disease.All 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, as there is insufficient data on its efficacy in people over 60. The vaccine is indicated for both those who have had dengue fever and those who have never been infected, and is the first vaccine released in Brazil for people with no history of contact with the virus.
However, Qdenga should not be administered to people who are 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 indicated that adverse reactions may occur, usually 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%
- Discomfort: 24%
- Weakness: 20%
- Fever: 11%
Observations
- Adverse reactions tend to be less frequent after administration of the second dose of Qdenga.
Global Impact
Dengue fever is currently endemic in more than 100 countries. The World Health Organization (WHO) estimates that up to 400 million people are infected each year. The disease ranges from a mild fever to severe forms, such as dengue hemorrhagic fever and dengue shock syndrome, which can be fatal.
Qdenga Vaccine Development
Given the widespread spread and impact of dengue, the need for an effective vaccine is clear. Until recently, control efforts have 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, the vaccine doses from the donated batch will be allocated to municipalities with more than 100,000 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, meaning it aims to protect against all 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 efficacy in animal models. Subsequent clinical trials were conducted in several phases:
- Phase 1: Evaluated the safety and immunogenicity of the vaccine in small groups of volunteers.
- Phase 2: Testing in a larger group to determine the optimal dosage and continue to assess safety.
- Phase 3: Large-scale trials to assess 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 that 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 immune response to Qdenga involves the production of neutralizing antibodies against all four serotypes of dengue virus. These antibodies help prevent infection and reduce the severity of disease if infection occurs.
Qdenga Effectiveness
Qdenga’s phase 3 clinical trials, known as TIDES (Trial to Evaluate Efficacy and Safety of a Dengue Vaccine), were conducted in several dengue-endemic countries. Results showed an overall efficacy of approximately 80% in preventing symptomatic dengue. Efficacy varied slightly between serotypes, but the vaccine provided substantial protection against all serotypes.
Long Term Protection
In addition to initial efficacy, follow-up studies indicate that Qdenga provides long-lasting protection. Trial participants continued to be monitored for several years to assess the duration of immunity, and 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 events related to the vaccine.
Post-Market Evaluations
Following regulatory approval, Qdenga continues to be monitored through post-marketing surveillance systems. These systems help identify any rare adverse events that may have been missed in clinical trials. To date, post-marketing safety data have 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 fever. With an effective vaccine, a decrease in infections, hospitalizations and deaths associated with the disease is expected. This would alleviate pressure on health systems, especially in endemic countries.
Economic Benefits
In addition to health benefits, reducing dengue 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 should 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 most prevalent, may face challenges in financing and distributing the vaccine. International initiatives and public-private partnerships will be essential to overcome these obstacles.
Viral Resistance
Another aspect to monitor is the possibility of viral resistance. Although Qdenga has shown efficacy against all four serotypes, viral evolution is a concern. Continued surveillance and research are needed to identify and respond to any changes in vaccine efficacy.
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 fever. With robust efficacy and a positive safety profile, it offers a powerful tool to reduce the global burden of the disease. However, successful implementation of the vaccine 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 worldwide.