The present invention is for a continuous-flow pathogen reduction apparatus and method, based purely on pathogen inactivation physical principles, for controlling or eliminating trans fusion-transmittable infections from emerging pathogens, pandemic viruses, and bioterrorism threats. The invention inactivates both nonenveloped and enveloped viruses as well as pathogenic bacteria and parasites in human plasma and biologies, while retaining the natural bioactivity, integrity and potency of the treated biologic. The method uses critic al, near-critical or supercritical fluids for viral and pathogen reduction of plasma and biologies. The apparatus is designed to rapidly process high volumes of plasma and biologies with high levels of pathogen reduction in a continuous flow fashion.