Story at a glance
- Dengue virus is transmitted to humans through mosquito bites.
- It can cause severe illness and death.
- A new vaccine candidate was more than 83 percent effective at protecting against hospitalizations over a three-year clinical trial.
Dengue virus is a mosquito-borne disease that can cause severe illness and death. Mostly occurring in tropical and sub-tropical parts of the world, there’s also the concern of range expansion due to warming climates. Currently, there is a vaccine but access is limited. For example, in the U.S., Dengvaxia is approved only for children 9 to 16 years of age who have had previous exposure to dengue, according to the Centers for Disease Control and Prevention. A new vaccine candidate from a team of international researchers looks very promising with a high efficacy rate and broad coverage.
Takeda Pharmaceutical Company Limited’s tetravalent dengue vaccine (TAK-003) is a live-attenuated dengue vaccine candidate that has been tested in various clinical trials since 2010. The researchers report in Clinical Infectious Diseases the most recent data from eight dengue-endemic trial locations over the course of three years. They tested this vaccine candidate in children aged 4 to 16.
The difficulty with developing a vaccine for dengue virus is that it has four main strains, and if you’ve had one strain you can still get sick from another one. Similarly, a vaccine that only protects against one strain would not protect you from other strains.
This vaccine is meant to protect against all strains. The initial phase 1 clinical trials were carried out for vaccines for dengue 1, 2 and 4 individually, says professor emeritus Sutee Yoksan, who is Advisor of the Center for Vaccine Development, Mahidol University, Thailand and worked on the vaccine candidate, in an interview with Asia Research News. Then they worked with the vaccine they had developed for dengue 2, but added certain key genes from the other three strains.
“You can think of this as having the backbone of a dengue 2 virus with immunogenic elements of the others in the mix. In this way, the immune [system] mounts an antibody response against all four dengue variants,” says Yoksan.
The overall three-year efficacy of the vaccine candidate was 62 percent against confirmed infection and more than 83 percent against hospitalization due to dengue virus disease. Efficacy was higher earlier in the clinical trials than at the end of the third year, although the authors note that they plan to evaluate whether to give a booster dose.
TAK-003 has already been approved for use in Indonesia, according to the company’s website. The vaccine candidate trial is registered in the U.S., but is not expected to complete phase 3 clinical trials until March 2024, according to government’s clinical trials website.
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