DENGUE VIRUS, SEROTYPE 2, EXPRESSING DENGUE VIRUS, SEROTYPE 3, SURFACE PROTEINS, LIVE, ATTENUATED

Dengue Virus, as the active substance in the vaccine Qdenga, is a live attenuated tetravalent vaccine that contains four dengue virus serotypes. The full registry name describes a dengue virus serotype 2 backbone that expresses surface proteins from serotypes 1, 3 and 4, together with the serotype 2 virus itself.^[1] The vaccine is authorised as a medicine in the European Union under authorisation record EU/1/22/1699/001, held by Takeda GmbH.^[1]

What is dengue virus?

Dengue Virus, in the form used in Qdenga, is a live attenuated tetravalent vaccine against dengue fever. It is a fixed combination of four live attenuated dengue virus components, each representing one of the four dengue serotypes.^[1] The product is authorised as a medicine in the EU, meaning it has completed the regulatory review process and is available for use. It is supplied as a powder and solvent for solution for injection under the name Qdenga.^[1]

How does dengue virus work?

As a live attenuated vaccine, Qdenga works by exposing the immune system to weakened forms of the four dengue virus serotypes. This triggers the body to produce antibodies against dengue viruses without causing the disease itself. The vaccine is designed to generate immune protection against all four dengue serotypes, which is important because infection with one serotype does not protect against the others.^[1] The current trial investigates a specific consequence of this immune response: whether the antibodies produced after vaccination also react with related flaviviruses, which could interfere with diagnostic blood tests for those infections.^[1]

Which conditions is dengue virus used or studied for?

• Dengue fever — Qdenga is authorised as a prophylactic vaccine to protect against dengue fever caused by any of the four dengue serotypes.^[1]
• Flavivirus diagnostic interference — the current trial studies whether vaccination affects serological testing for tick-borne encephalitis virus (TBEV), yellow fever virus (YFV), Zika virus (ZIKV) and Japanese encephalitis virus (JE).^[1]

How is dengue virus given?

Qdenga is given as a subcutaneous injection. The vaccine is supplied as a powder and solvent for solution for injection, and each dose is 0.5 millilitres.^[1] In the current trial, participants receive two doses of the vaccine.^[1]

What do the clinical trials show?

One clinical trial is registered in the EU Clinical Trials Information System for this substance. The trial is an open, non-randomised Phase 3 study that has been authorised but has not yet started.^[1] It plans to enrol 45 Swedish travellers.^[1]

What is the trial measuring?

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 levels before vaccination.^[1] The study aims to assess whether the vaccine causes significantly elevated levels of cross-reactive IgG antibodies against these related flaviviruses, which could interfere with serological diagnostic tests.^[1]

What side effects are known?

The clinical trial data provided does not include information on side effects. As an authorised medicine, the product information for Qdenga contains the known side effect profile, but this is not part of the registry data supplied for this page.