Qdenga is a live dengue vaccine authorised in the EU and prequalified by WHO. Here is who it is for, how it is given, and what the evidence shows.
What Qdenga is and where it is authorised
Qdenga is a dengue vaccine. The European Medicines Agency describes it as a live, attenuated tetravalent vaccine, which means it contains weakened versions of all four dengue virus serotypes. The agency granted it EU marketing authorisation on 5 December 2022, for preventing dengue disease in people from 4 years of age. That covers adults, adolescents and children. The World Health Organization prequalified the same vaccine, known in its documents as TAK-003, on 10 May 2024. Prequalification makes a vaccine eligible for procurement by United Nations agencies, including UNICEF and the Pan American Health Organization. Two dengue vaccines now hold WHO prequalification. The other is CYD-TDV. Qdenga is therefore a licensed product in Europe and a prequalified product globally, though authorisation is not the same as a recommendation for every person.
How the vaccine is given
Qdenga is given as an injection under the skin of the upper arm. The schedule is two injections, three months apart. The European Medicines Agency sets out that schedule for the authorised European product. WHO states the same minimum interval of three months for TAK-003 and advises against shortening it. A delayed second dose does not mean starting the series again. That matters for travellers who book a trip late, because the two doses cannot be compressed into a single short window. Anyone planning travel should therefore allow enough time before departure. A travel clinic can confirm the timing that fits a specific itinerary. The vaccine does not prevent every case of dengue, so it sits alongside measures that reduce mosquito bites rather than replacing them.
The evidence behind the authorisation
The European Medicines Agency describes a main study of about 20,000 children aged 4 to 16 years. Confirmed dengue fever cases fell by 80 percent: 61 cases among 12,700 vaccinated children, compared with 149 among 6,316 children who received a placebo. Hospitalisation for dengue fell by 90 percent: 0.1 percent of vaccinated children, 13 of 12,700, compared with 1.0 percent of the placebo group, 66 of 6,316. These are the figures behind the European authorisation decision. They describe a trial population of children, so they do not map directly onto every adult traveller. WHO also notes that TAK-003 does not prevent all cases. The balance of benefit therefore depends on a person's age, health, and the intensity of dengue transmission where they are going.
Who WHO recommends it for
WHO recommends TAK-003 for children aged 6 to 16 years in settings with high dengue transmission intensity. It does not currently recommend programmatic use in children under 6 years, because efficacy is lower in that age group and seropositivity is generally low. For travel, the picture is more individual. WHO states that travellers previously infected with dengue may benefit from vaccination, while benefits are lower for travellers who have never had dengue and are therefore seronegative in tests. National guidance can differ from global guidance, so a clinician or travel clinic should assess the personal risk. WHO also does not recommend programmatic use in low to moderate transmission settings until the efficacy and risk profile for serotypes 3 and 4 in seronegative people has been assessed more thoroughly.
Who should not receive it
The European Medicines Agency states that Qdenga must not be used in people with hypersensitivity to a previous dose, people with weakened immune systems, or women who are pregnant or breastfeeding. WHO gives a closely matching list and adds that it should not be given to people planning pregnancy within one month, people who are breastfeeding, people with immune deficiency, or people with symptomatic HIV or asymptomatic HIV with impaired immune function. These are the groups where a live, attenuated vaccine carries specific concern, either for the recipient or for a pregnancy. Anyone in these categories should not treat this article as clearance to proceed. They should discuss dengue prevention with a qualified clinician, who can weigh the alternatives and explain how to reduce mosquito exposure.
Side effects and how to judge them
The most common side effects are pain and redness at the injection site, headache, muscle pain, feeling generally unwell and weakness. Fever occurs in up to 1 in 10 people. The European Medicines Agency says these reactions are usually mild to moderate and resolve within a few days. That is broadly the profile expected from a vaccine, rather than a sign that something has gone wrong. A reader who feels unwell after a dose should still seek advice if symptoms are severe or persistent, or if they are unsure. Mild soreness at the injection site is not usually a reason for alarm, but neither should it be hidden from a clinician. Reporting suspected side effects to a national medicines authority helps other people as well.
Travel context and bite prevention
Dengue is not found in the UK, but it is common in tropical areas, including parts of Africa and Asia, Central and South America, the Caribbean, the Pacific islands and some southern areas of North America. There is also seasonal risk from spring to autumn in parts of southern Europe, including Croatia, France, Italy, Spain and Madeira. The NHS advises long sleeves and trousers, especially in the early morning and early evening, insect repellent ideally containing DEET, closed windows or blinds and screens, and sleeping under an insecticide-treated net, including during the day. WHO reports that global dengue cases are likely to rise and spread geographically with climate change and urbanisation. Physical barriers and repellents remain real protection when correctly specified, intact and correctly used.
Sources
- Qdenga | European Medicines Agency (EMA): European Medicines Agency
- Vaccines and immunization: Dengue: World Health Organization
- WHO prequalifies new dengue vaccine: World Health Organization
- Dengue - NHS: NHS
This article is general information, not medical advice. Ask a doctor or pharmacist about your own health.