WHO approves second vaccine against the mosquito-borne disease dengue as outbreaks intensify

The World Health Organization on Wednesday authorized a second dengue vaccine, a move that could provide protection for millions worldwide against the mosquito-borne disease that has already sparked numerous outbreaks across the Americas this year.

In a statement on Wednesday, the U.N. health agency said it approved the dengue vaccine made by the Japanese pharmaceutical Takeda, recommending its use in children between six to 16 years old living in regions with high rates of dengue. The two-dose vaccine protects against the four types of dengue.

Takeda’s dengue vaccine, known as Qdenga, was previously given the nod by the European Medicines Agency in 2022.

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WHO’s approval now means that donors and other U.N. agencies can purchase the vaccine for poorer countries.

Studies have shown Takeda’s vaccine is about 84% effective in preventing people from being hospitalized with dengue and about 61% effective in stopping symptoms.

WHO’s Rogerio Gaspar, director for the agency’s approvals of medicines and vaccines, said it was "an important step in the expansion of global access to dengue vaccines." He noted it was the second immunization the U.N. agency had authorized for dengue.

The first vaccine WHO approved was made by Sanofi Pasteur, which was later found to increase the risk of severe dengue in people who had not previously been infected with the disease.

There is no specific treatment for dengue, a leading cause of serious illness and death in roughly 120 Latin American and Asian countries. While about 80% of infections are mild, severe cases of dengue can lead to internal bleeding, organ failure and death.

Last week WHO reported there were 6.7 million suspected cases of dengue in the Americas, an increase of 206% compared with the same period in 2023. In March, authorities in Rio de Janeiro declared a public health emergency over its dengue epidemic and the country began rolling out the Takeda vaccine, aiming to inoculate at least 3 million people.

Last year WHO said cases of dengue have spiked tenfold over the last generation, with climate change and the increasing range of the mosquitoes that carry dengue partly to blame for the disease’s spread.