What happens in the brain when a virus takes hold — and why do some people never recover?Dr Avindra Nath, NIH neurovirologist and Clinical Director of NINDS, has spent his career studying the neurological impact of viral infections — from HIV and Ebola to ME/CFS and Long COVID.In this episode he explains how viral remnants persist in the body long after acute infection, how immune exhaustion drives ongoing symptoms, and what the NIH’s landmark 2024 deep-phenotyping study revealed about ME/CFS — including striking sex differences in immune response that could change how we treat these conditions.He also shares details of three active NIH clinical trials for Long COVID:Viral Reservoir StudyIVIG StudyCheckpoint Inhibitor Study (pembrolizumab — enrolment opening April 2026)Emily Kate and Gez break down the science and discuss the controversies around the NIH team’s methodology.