said Tuesday a key trial showed its dengue vaccine protected children against the widespread tropical disease, raising hopes that a new weapon against the mosquito-borne infection without safety concerns could be approaching.
Yet a full and detailed assessment of the Takeda vaccine’s benefit and risks will have to wait, because the company declined to detail the results until they are published in a medical journal.
An estimated 390 million people are infected with the mosquito-borne dengue virus in tropical regions around the world each year. But only one licensed vaccine, Dengvaxia from
has been available so far to offer protection, and it has safety problems.
Since Sanofi disclosed the safety issues in 2017, public health experts and governments around the world have been looking forward to Takeda’s results.
Takeda said its vaccine, called TAK-003, protected children for at least one year against dengue infection caused by four different types of the virus in the late-stage trial. No safety problems were observed with the vaccine, Takeda said.
“We feel very good about the results we have so far,” said Rajeev Venkayya, president of Takeda’s Global Vaccine Business Unit.
The trial, which began in late 2016, included more than 20,000 children between 4 and 16 years of age in eight countries. The young subjects received two doses either of the drug or a placebo three months apart.
The children were then assessed for dengue a year after their second dose. Researchers are still monitoring the subjects.
Dr. Venkayya said the company aimed for the specific results to be published soon. “We’d rather talk about the data when we’re able to publish essentially everything we have in a peer-reviewed journal so we can have a discussion about everything,” he said.
In some cases the detailed results haven’t lived up to the “top line” news releases issued earlier by companies.
Even if the data are borne out, the vaccine won’t be on the market soon. Takeda will wait until it has more follow-up data before applying to governments for approval, Dr. Venkayya said.
As part of the trial, the company is monitoring subjects for safety problems and to see how well the vaccine protects them against dengue, he said. The data will include results in children who had been infected with dengue before immunizations, as well as those who hadn’t.
Nearly four billion people —more than half of the world’s population—are at risk of dengue infection. It is among the 10 threats to global health in 2019 identified by the World Health Organization.
About 96 million people who are infected with the mosquito-borne virus develop a flulike illness, sometimes called “breakbone fever” for the excruciating muscle and joint pain it can cause. About two million cases a year are severe, with internal bleeding or shock, and about 20,000 people die.
About five dengue vaccine candidates are in development, according to the WHO, with two in Phase 3 trials—Takeda’s and another led by the U.S. National Institute of Allergy and Infectious Diseases.
Concerns about safety are paramount. In late 2017, Sanofi, based in France, said its Dengvaxia product, first approved for sale in 2015, could in some cases worsen rather than prevent symptoms of the debilitating tropical disease.
Because there are four types of dengue, a person can be infected with the virus more than once, and a secondary infection is often more severe than the first. For some people who had never been infected, Dengvaxia in effect could mimic an initial infection.
Sanofi made its disclosure as dozens of children who had been immunized in the Philippines fell ill, with some hospitalizations and deaths. The government suspended the mass vaccination program. Sanofi and health officials say there isn’t evidence of a link between the vaccine and the deaths.
The WHO and Sanofi recommend against giving Dengvaxia to people who haven’t been infected with dengue previously. A Sanofi spokeswoman said Dengvaxia is effective for people who have had dengue before.
Write to Betsy McKay at firstname.lastname@example.org