A target product profile and roadmap for Japanese encephalitis diagnostics in endemic areas in the context of other flaviviruses.

Japanese encephalitis (JE) virus (JEV) is a leading cause of neurological infection in the Asia-Pacific region with devastating socioeconomic consequences. We aimed to develop a target product profile (TPP) for JE diagnostics in endemic areas in the context of other flaviviruses, to better define improvements needed for patient management and public health. Thematic experts were identified from a scoping review, World Health Organization and Encephalitis International databases, as well as author networks. Initial interviews were performed with selected experts to inform a draft TPP document and start a Delphi process, aiming for consensus of ≥75% on each characteristic. A one-day meeting facilitated in-depth discussion, with breakout groups and electronic voting to develop the final TPP document. In total, 460 participants were invited. Five interviews enabled drafting a TPP. Two iterative surveys were completed by 44 respondents, including clinicians, scientists, and public health experts from 15 countries. A hybrid meeting was attended by 42 participants. Seven priority characteristics were discussed, and consensus was achieved for six; no clear consensus was reached for the preferred test sensitivity and specificity, with 73% agreement. Discussion points and areas of expert consensus were consolidated into a roadmap for development and implementation to guide future work. A diverse group of health professionals agreed that improved diagnostics for JE are needed, and that a priority is a test for patient management that detects JE alongside other relevant flavivirus infections. There was a mandate for a rapid diagnostic test (RDT), and it was suggested that this could be implemented in a two-tiered diagnostic algorithm. The final TPP is presented in the paper; this aims to help define the updates needed to better support patient management and public health interventions, to provide a strategic reference document to drive innovation and improve clarity for JE diagnostic test developers.