In response to the growing global burden of dengue fever, a…
In response to the growing global burden of dengue fever, a biotechnology company developed a new tetravalent dengue vaccine. Early phase clinical trials showed the vaccine was safe and generated an immune response. The company now seeks to evaluate whether the vaccine is effective at preventing symptomatic dengue infections in high-incidence areas. They enroll 10,000 healthy adult volunteers in Brazil, where dengue transmission is high. Participants are randomly assigned to receive either the dengue vaccine or a placebo. Over the next 18 months, participants are monitored for the development of laboratory-confirmed dengue infection. What type of study design is being conducted?