Dengue fever Trials in Disease

Study on the Effects of the Dengue Vaccine Qdenga on Antibody Levels in Swedish Travelers

This clinical trial is examining how the Qdenga vaccine affects antibody levels in people who receive it. Qdenga is a vaccine designed to prevent dengue fever, a mosquito-borne viral disease that causes high fever, severe headache, joint pain, and other symptoms. The vaccine contains a weakened form of the virus that helps the body build immunity without causing illness.

Main goal: The primary focus of this study is to understand how the Qdenga vaccine influences the levels of certain antibodies in the blood. Researchers are particularly interested in whether the vaccine causes increased levels of antibodies that might also react with other similar viruses, such as tick-borne encephalitis virus, yellow fever virus, Zika virus, and Japanese encephalitis virus. The study will compare antibody levels before vaccination and 90 days after receiving two doses of the vaccine.

Who can participate: To be eligible for this study, you must be at least 18 years old and able to participate in all aspects of the study. You need to provide signed written consent and have a negative pregnancy test if you are a woman of childbearing potential. Most importantly, you should be planning to travel to a country where dengue fever is common, and the decision to get vaccinated should be made together with your doctor following Swedish medical guidelines.

Who cannot participate: You cannot join this study if you have serious health conditions that could interfere with the research, have received other vaccines recently, or have a history of severe allergic reactions to any vaccine component. Pregnant women, those planning to become pregnant during the study, or breastfeeding mothers are not eligible. People with immune system disorders, those taking medications that affect the immune system like steroids, or those who have recently participated in another clinical trial cannot take part. A history of drug or alcohol abuse or any other condition that makes you unsuitable for the study according to the doctor's assessment will also exclude you.

What happens during the trial: Participants will receive two doses of the Qdenga vaccine given as injections under the skin. After both doses are administered, blood samples will be taken to measure antibody levels and assess how well your body is responding to the vaccine. The monitoring period extends to 90 days after the second dose, with the study expected to conclude by November 2027.

Investigational drug: Qdenga is the vaccine being tested in this trial. It works by stimulating the body's immune system to produce antibodies that can recognize and fight the dengue virus if you are exposed to it in the future. This trial specifically aims to understand whether the vaccine also affects antibody levels for other related viruses.