NEWS

28 October 2026

Researchers help to answer a question dogging the development of improved vaccines against the mosquito-borne disease.

People who are infected with dengue virus for a second time often develop severe disease. Credit: Mamunur Rashid/NurPhoto via Getty

Infecting people with a weak strain of dengue virus is helping researchers to unravel the disease’s bizarre effects on the immune system.

Dengue is spread when someone is bitten by an infected female Aedes mosquito. The viral disease kills around 40,000 people every year, with up to 400 million infected annually. Bangladesh and Kenya are among the countries battling a deadly outbreak. Although most adults survive their first brush with the disease, people who are exposed to a second, different strain of dengue virus often develop more severe symptoms.

This unusual quirk has complicated dengue vaccine development.…