The world’s first dengue vaccine only works for those with prior infections, a disappointing revelation for a drug many hoped would effectively fight a virus that disproportionately kills scores of African who don’t have access to quality medical care, ABC News reported.
“For those not previously infected by dengue virus…the analysis found that in the longer term, more cases of severe disease could occur following vaccination. These findings highlight the complex nature of dengue infection,” the Paris-based drugmaker Sanofi said, in a statement released late Wednesday.
Sanofi said its scientists recently analyzed six years of patient data and found that the vaccine protects people against further infection if they’ve already been infected with dengue. The vaccine can lead to more severe disease for those who haven’t previously contracted the illness. Dengue is a mosquito-borne viral infection that causes severe flu-like illness, which can potentially create lethal complications, according to the World Health Organization. About 16 percent of cases occur in sub-Sahara Africa, which has seen many outbreaks of the illness that is often misdiagnosed as malaria throughout the continent. Although that’s a relatively small percentage, African countries lack the resources to properly diagnose and treat the illness. There are an estimated 50 million cases of dengue infection each year, concentrated in about 34 African countries.
The vaccine has been sold widely in multiple countries across Asia, Latin America and Africa, where the disease is prevalent. Regulators in those countries are urged to update the vaccine’s label so doctors avoid using it on patients who have never had the disease. There’s no specific treatment for dengue and no other licensed vaccines on the market. This news is also a significant financial setback for Sanofi, which took an estimated $118 million loss with this revelation. Forecasts had predicted that the vaccine would generate sales of $840 million in 2020, according to Bloomberg News.