Contrary dengue vaccine response hints at possible problems with Zika

“It’s happened. We have a vaccine that enhances dengue,” said Scott B. Halstead, MD, talking about a phenomenon whereby the dengue vaccine sets up dengue-naive recipients for severe disease. Halstead, the leading figure in dengue research in the past 50 years, is referring to CYD-TDV (Dengvaxia, Sanofi Pasteur), the first dengue vaccine approved by the World Health Organization in April, and now licensed for use in five countries. When Halstead, a former senior advisor of the Dengue Vaccine Initiative and the founder of Children’s Vaccine Initiative, first saw the 3-year results of the vaccine published in the New England Journal of Medicine last summer, he immediately saw a problem in the data. “It’s clear as the nose on my face: Vaccine recipients less than 5 years old had five to seven times more rates of hospitalizations for severe dengue virus than placebo controls.” ADE primes subjects for severe illness Halstead is describing a problem...