Sanofi's Dengvaxia could do more harm than good in certain settings, study says

Already facing a slower-than-expected launch, Sanofi’s $1.5 billion dengue vaccine Dengvaxia could do more harm than good if used in the wrong setting, a new study says.

Published in Science, the study included an analysis of all publicly available clinical data for Dengvaxia--spanning 30,000 people in 10 countries--and found that, if used in areas of low dengue prevalence, the vaccine could make infections worse. But, the authors stressed, the vaccine can help in areas where dengue is more common, by helping reduce illnesses and hospitalizations by 20% to 30%.

The reason? Dengue is different from most infectious diseases in that a person’s second infection typically is much more serious than the first, according to Imperial College London. Researchers from Johns Hopkins Bloomberg School of Public Health, Imperial College London and the University of Florida conducted the work.

If a person who hasn’t had the infection receives Dengvaxia, the vaccine “acts very much like a natural infection but without making recipients sick,” the researchers said in a release. Then, if that person encounters the virus naturally, their immune system could process it as a second infection that’s much more severe.

Sanofi has acknowledged that Dengvaxia doesn’t work well in those who haven't had a dengue infection, according to the release. The company said it intends to provide FiercePharma with more information.

The researchers said they hope the study can inform decisions about Dengvaxia vaccination strategies. The three-dose vaccine took Sanofi 20 years and $1.5 billion to develop, and so far, the Philippines and Brazil’s Paraná state have unveiled vaccination campaigns utilizing the shot.


The findings are in line with WHO guidelines, issued in April, that Dengvaxia be used as part of a broader dengue control strategy in areas where the virus is prevalent.

But since its launch, the vaccine has tread somewhat of a rocky path. In estimates for 2016, Sanofi figured it could rake in €200 million with Dengvaxia; after turning in just €1 million in the second quarter, the company said it would miss that figure. The company placed some of the blame for slow sales on economic and political turmoil in Latin America.

Launched late last year, the vaccine is currently available in a handful of countries--Sanofi has said it’s hoping for 20 approvals--and could see competition from Takeda’s DENVax by 2020. An NIH candidate is currently in a Phase III trial in Brazil, and last week the U.S. government and India unveiled a dengue vaccine collaboration they’re working to finalize.

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