Bioethics of establishing a CHIM model for dengue vaccine development

Controlled human infection models (CHIM) have been used in vaccine development to up-select and down-select potential vaccine candidates and to provide proof of vaccine efficacy, and have also been used as a basis for licensure of vaccines for cholera and typhoid by regulatory agencies.

Dengue fever results in ∼400 million infections a year and is of significant health concern especially in India. There are currently no antivirals for the disease and the only licensed vaccine for dengue is not widely used owing to safety concerns. Controlled dengue human challenge models (DHCM) are currently being used to assess the efficacy of vaccines in development for dengue.

Conducting CHIM studies in India especially for evaluation of dengue vaccine candidates will be hugely beneficial as the disease is endemic to India and hence the effect of pre-exposure to the virus on vaccine safety and efficacy can be established. However, to date no CHIM studies have been conducted in India and there is a need to educate ethics committee members, policy makers and the public on the importance of such studies and what they entail.