On Jan. 26, 2021, NIH researchers announced that an investigational anti-HIV antibody delivered intravenously once every eight weeks safely and effectively prevented acquisition of HIV strains sensitive to that antibody, but did not significantly reduce overall HIV acquisition after 80 weeks among participants in two multinational clinical trials.

Known as the Antibody-Mediated Prevention (AMP) Studies, the Phase 2b trials were sponsored and funded by the National Institute of Allergy and Infectious Diseases. The studies are being conducted jointly by the HIV Vaccine Trials Network and HIV Prevention Trials Network.