DAVID GREENE, HOST:
The World Health Organization labels dengue one of the top 10 threats to global health in 2019. This mosquito-borne disease also known as breakbone fever sickens roughly a hundred million people every year, and there's no specific drug to treat it. But that might be changing. In clinical trials, a new vaccine appears to protect most children against the virus and also cut severe, potentially fatal cases by 95%. Here's NPR's Jason Beaubien.
JASON BEAUBIEN, BYLINE: Dengue doesn't get as much attention as malaria or HIV or Ebola, but its impact globally is huge and growing. So far this year, Brazil alone has had more than 2 million cases. There were major epidemics in the Philippines, Indonesia and Bangladesh. Guam just recorded its first outbreak in 75 years.
DEREK WALLACE: This is the fastest-spreading mosquito-borne viral disease on the planet.
BEAUBIEN: Derek Wallace is the head of Takeda Pharmaceutical's Global Dengue Program. Wallace and his colleagues have been testing a new vaccine against the mosquito-borne disease.
WALLACE: Dengue is a very important disease across a large part of the world. Nearly half the world's population's at risk of dengue.
BEAUBIEN: It causes joint pain, headaches and nausea. It can even lead to shock, organ failure and death. In a study published this week in the New England Journal of Medicine, Wallace and his team report that their new vaccine appears to be safe and protected kids against all four strains of the dengue virus.
WALLACE: We're thrilled with the results we've seen in our pivotal efficacy study. Vaccine efficacy of 80% has the potential to have a massive impact on the significant public health burden of dengue.
BEAUBIEN: The trial was on nearly 20,000 children in seven countries. Wallace says Takeda's new product is fundamentally different from the world's first licensed dengue vaccine Dengvaxia, which caused a major scandal two years ago in the Philippines. After nearly a million Filipino children had been vaccinated with Dengvaxia, its manufacturer announced that the inoculation might actually make subsequent dengue infections worse in some kids. It was a public health fiasco that significantly undermined many Filipinos' confidence in vaccines in general.
Wallace says the Takeda vaccine is built around a live but weakened dengue virus while the older Dengvaxia one is built on a strain of the yellow fever virus.
WALLACE: We have not seen any evidence of an increase in severe dengue as a result of vaccination in this study, but it is important that we continue to look at this over a longer period of time.
BEAUBIEN: Stephen Waterman, the head of the U.S. Centers for Disease Control and Prevention's Dengue Branch, says an effective and safe dengue vaccine is very much needed. If the new Takeda product is really as good as it appears, Waterman says it could be an important tool against this global scourge. But he still wants to see more data.
STEPHEN WATERMAN: Developing dengue vaccines has been difficult because of the four different viruses involved and the need to package four different viruses into one vaccine.
BEAUBIEN: A person's antibodies against one strain at times can amplify the effects of another strain. Waterman calls it a tricky disease.
WATERMAN: So I think we would want to see the full trial data over a longer period of time to be convinced that the efficacy is that high.
BEAUBIEN: Takeda's vaccine also still needs to win regulatory approval before it can be sold. Company officials, however, are confident they'll get it. This week, Takeda opened a 100 million euro factory in Germany exclusively to manufacture this new dengue vaccine.
Jason Beaubien, NPR News.
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