A drug once designed for dengue virus, then quietly abandoned by industry, is suddenly back in the spotlight, and it may be exactly what the global health community has been waiting for. A new study suggests that this antiviral didn’t just slow the dengue virus, it blocked viral replication and significantly reduced infection rates at high doses. Now, scientists are racing to map its path toward clinical trials. If it holds up, this once-side-lined molecule could become the first targeted therapy for a disease that has affected hundreds of millions.