In this crossover episode with AIDS' Existential Moment, recorded during the International AIDS Conference in Montreal, Canada, on July 30th, Jeff Sturchio speaks with Dr. Mark Feinberg, president and CEO of the International AIDS Vaccine Initiative (IAVI). In this interview, Dr. Feinberg addresses the continued progress in HIV prevention and treatment seen in recent years and outlines the challenges still faced in translating this progress into meaningful impact on the lives of people affected by HIV/AIDs. Turning the tide against HIV will require a decline in new infections, which highlights the need for an effective HIV vaccine. Dr. Feinberg discusses the exciting and fascinating progress being made in research on broadly neutralizing antibodies and how the lessons learned from failed vaccine efficacy trials have informed new approaches that have considerable promise for enhancing understanding of how to design effective HIV vaccines. He also explains clearly and compellingly some of the basic biology that makes HIV such a wily and difficult adversary due to its genetic diversity compared to such other pathogens as Ebola and SARS-COV-2. New tools in such areas as mRNA delivery and computational biology are being brought to bear in the search for an HIV vaccine. Dr. Feinberg concludes by expressing his hope that the scientific challenges of HIV will continue to attract the next generation of creative young scientists. Mark Feinberg leads a global team at IAVI working to advance the development of vaccines and other biomedical innovations to protect against infection with HIV, TB, and other infectious diseases that have a disproportionate impact on low-income countries. Prior to joining IAVI in late 2015, Feinberg served as chief public health and science officer with Merck Vaccines. Dr. Feinberg holds an M.D. and a Ph.D. from Stanford University, and a B.A. degree from the University of Pennsylvania.