The CDC's Advisory Committee on Immunization Practices (ACIP) has now recommended using Sanofi's dengue vaccine, Dengvaxia, in the US, with specific restrictions. The vaccine is only to be used for children aged 9–16 who live in endemic areas and who have evidence with a specific diagnostic test of prior dengue infection.
Dengue is a mosquito-borne virus found throughout the world, primarily in tropical or subtropical climates. Cases had steadily been increasing to 5.2 million in 2019, and the geographic distribution of cases is broadening with climate change and urbanization. About half of the world's population is now at risk.
The dengue virus has four serotypes. The first infection may be mild or asymptomatic, but the second one can be life-threatening because of a phenomenon called antibody-dependent enhancement.
Dr Gabriela Paz-Bailey
The lead author of the new recommendations is Gabriela Paz-Bailey, MD, PhD, Division of Vector-Borne Diseases, Dengue Branch, CDC. She told Medscape Medical News that during the second infection, when there are "low levels of antibodies from that first infection, the antibodies help the virus get inside the cells. There the virus is not killed, and that results in increased viral load, and then that can result in more severe disease and the plasma leakage" syndrome, which can lead to shock, severe bleeding, and organ failure.
