Sanofi's controversial dengue vaccine wins FDA approval, with a raft of caveats
Sanofi’s controversial dengue vaccine, which took two decades to develop, has made it across the FDA finish line — but it wasn’t pretty. Less than a month after a panel of experts delivered mixed reviews for the shot, on Wednesday, the US health regulator sanctioned the use of Dengvaxia as the first-ever product to prevent the mosquito-borne disease in certain individuals who have previously contracted dengue and who live in areas rife with the disease.
The FDA has limited the use of the vaccine in individuals aged 9 to 16 who have laboratory-confirmed previous dengue infection and live in areas where the disease is endemic, such as Puerto Rico, the US Virgin Islands and American Samoa. Originally, Sanofi $SNY had sought to secure approval for people aged 9 through 45, but the FDA advisory panel last month foiled that bid, only agreeing to recommend its use in children.
Dengvaxia — which is administered as three separate injections — was found to be roughly 76% effective in preventing symptomatic dengue disease in individuals 9 through 16 years of age who previously had laboratory-confirmed dengue disease, the FDA noted. But in the United States and its territories, no available tests have been cleared by the FDA to determine a previous dengue infection, Sanofi said.
The French drugmaker once had blockbuster dreams for the world’s first dengue vaccine, but that hope was massacred after it was forced to concede in late 2017 that Dengvaxia could enhance the risk of severe dengue in children who had never been exposed to the virus — only after the Philippines used $70 million worth of the shot in a mass vaccination campaign for 800,000 children.
But even before the Philippines’ public health crisis, experts had warned that vaccination with Dengvaxia in those who had not already been infected by one of the four different serotypes of the virus faced a potentially life-threatening fever upon a subsequent infection. This is because their bodies would likely treat the first real dengue infection as their second, thanks to the vaccine. According to the FDA, roughly 95% of all severe/hospitalized cases of dengue are associated with second dengue virus infection.
In March, Philippine officials said they were preparing criminal charges against Sanofi, in connection with 10 deaths they said were linked to the vaccine. Sanofi opposed their findings.
The virus is widespread across the tropics. Severe dengue was first recognized in the 1950s during dengue epidemics in the Philippines and Thailand, currently affects most Asian and Latin American countries, and is considered a leading cause of hospitalization and death among children and adults in these regions, according to the WHO. The CDC estimates that each year, about 400 million dengue virus infections occur globally. The dengue virus is carried by female Aedes aegypti mosquitoes (and to a lesser extent, Ae. albopictus) — the same species that also transmits chikungunya, yellow fever and Zika.
The French drugmaker has earned a tropical disease priority review voucher — granted to drugmakers to reward drug/vaccine development for tropical diseases that typically don’t get much attention — in connection with the approval. Some of these vouchers have been previously sold for hundreds of millions of dollars.
Dengvaxia has already been cleared for use in 19 countries, and last year was approved by the European Union for individuals aged 9 to 45 years who have been infected with dengue virus before and who live in areas where the infection is endemic.
Japan’s Takeda has a rival dengue vaccine in late-stage development.