DENGUE VIRUS, SEROTYPE 2, EXPRESSING DENGUE VIRUS, SEROTYPE 4, SURFACE PROTEINS, LIVE, ATTENUATED

Table of contents

• What is Qdenga?
• How does Qdenga work?
• Which conditions is Qdenga used or studied for?
• How is Qdenga given?
• What do the clinical trials show?
• What side effects are known?

What is Qdenga?

Qdenga is the trade name for a dengue tetravalent vaccine containing live, attenuated dengue virus. The full active substance name in the registry is DENGUE VIRUS, SEROTYPE 2, EXPRESSING DENGUE VIRUS, SEROTYPE 4, SURFACE PROTEINS, LIVE, ATTENUATED, together with three related constructs expressing surface proteins of serotypes 1, 3 and 4 on a serotype 2 backbone. The product is registered as Qdenga powder and solvent for solution for injection and is manufactured by Takeda GmbH.^[1]

Qdenga is already authorised as a medicine in the European Union, under authorisation record EU/1/22/1699/001. It is classified in the therapeutic areas of diagnosis, immune system phenomena, and virus diseases. The substance is a fixed combination of four live, attenuated dengue virus components in one product.^[1]

How does Qdenga work?

Qdenga is a live, attenuated vaccine. It contains weakened forms of dengue virus that cannot cause disease but can still train the immune system. The vaccine uses a dengue virus serotype 2 backbone that has been modified to express surface proteins from dengue virus serotypes 1, 3 and 4, alongside the original serotype 2 component. This tetravalent design aims to generate immune responses against all four dengue serotypes.^[1]

The registered trial is investigating a specific immunological question: whether vaccination with Qdenga causes elevated levels of cross-reactive IgG antibodies against other flaviviruses, namely tick-borne encephalitis virus (TBEV), yellow fever virus (YFV), Zika virus (ZIKV) and Japanese encephalitis virus (JE). These cross-reactive antibodies could interfere with serological diagnostic tests for those infections in travellers.^[1]

Which conditions is Qdenga used or studied for?

• Prevention of dengue fever — Qdenga is authorised for the prevention of dengue fever caused by dengue virus serotypes 1, 2, 3 and 4.^[2]
• No medical condition in the trial — the registered trial enrols healthy Swedish travellers who receive Qdenga as a prophylactic vaccine, not as treatment for an existing illness.^[1]

How is Qdenga given?

Qdenga is supplied as a powder and solvent for solution for injection. It is administered by subcutaneous injection, meaning the injection is given under the skin. The dose used in the registered trial is 0.5 ml. A paediatric formulation in a pre-filled syringe is also listed in the paediatric investigation plan records.^[1][2]

What do the clinical trials show?

One clinical trial is registered for this substance in the EU Clinical Trials Information System. It is a Phase 3, open, non-randomised trial with a planned enrolment of 45 participants. The trial status is authorised, meaning it has received regulatory approval and is proceeding.^[1]

The trial population consists of Swedish travellers receiving the Qdenga vaccine. The primary outcome is the level of IgG antibodies in serum against TBEV, YFV, ZIKV and JE at day 90 after two doses of Qdenga, compared to before vaccination. The aim is to assess whether Qdenga causes significantly elevated cross-reactive IgG antibody levels that could interfere with flavivirus serological diagnostics.^[1]

The study is interventional and open-label, meaning participants and researchers know which vaccine is being given. It is not randomised, so all participants receive the same Qdenga vaccination schedule of two doses.^[1]

What side effects are known?

The supplementary source used for this page, a paediatric investigation plan record from the MHRA, does not list side effects for Qdenga. No side effect information is therefore included here.