Project Summary The scientific and public health response against HIV/AIDS in the past four decades has been remarkable and unprecedented. Yet HIV transmission continues in many populations at unacceptably high rates despite testing and treatment availability, largely driven by stigma and discrimination and other social and structural determinants. IAS 2021 will be the key global scientific convening to review progress against remaining challenges in controlling the epidemic. Significant new insights that are expected to be shared at IAS 2021 include basic work on virology, immunology and HIV pathogenesis with a continued focus on the functional cure/remission agenda. Clinical research in HIV is entering a new era of longer acting and injectable formulations which will be highlighted at IAS 2021, along with the remaining challenges of adherence, pill fatigue, and multi-drug resistant variants. Pediatric clinical care issues will be a further key topic where the advances in newer integrase inhibitor-based regimens for infants and children will be a primary focus. In the prevention field, the finding of superiority for long-acting injectable cabotegravir as PrEP marks the beginning of a new era, with further evidence expected in this regard at IAS 2021, along with early data on the co-formulations of long-acting injectables with other products for contraception, opioid dependence, and other health conditions. In the implementation science field innovative testing, prevention, treatment, and surveillance modalities will feature prominently at IAS 2021. Finally, the COVID-19 pandemic is expected to be among the defining themes across all scientific tracks against the background of treatment interruptions worldwide and the many remaining uncertainties regarding HIV/SARS- CoV-2 interactions. While the IAS is making parallel provisions for shifting to a fully virtual delivery format if mandated by the state of the COVID-19 pandemic, IAS 2021 is planned to take place in Berlin from 18-21 July 2021, with a strong virtual presence to ensure broad access (expected attendance of 6,000 delegates). It will provide a critical platform for HIV science to re-convene in a country now characterized by a celebration of diversity and zero discrimination. Berlin is at the heart of Europe, with close connectivity to the most HIV-affected region in Europe?Central and Eastern Europe, in particular Ukraine, and the Russian Federation, where, in marked contrast to Germany, rights-based approaches to HIV programming are constantly challenged. Specific aims of IAS 2021 are to: 1. Accelerate basic science and clinical innovation for the development and application of person-centered, precision medicine for HIV, including pathogenesis, transmission, vaccines, remission and a functional cure. 2. Advance inter-disciplinary collaboration in clinical research to improve integrated care across all life stages and accelerate updates to treatment guidance especially for low and middle-income countries, infected children, persons with HIV, TB, viral hepatitis and COVID-19 infection; 3. Strengthen HIV prevention research to improve biomedical, behavioral and structural interventions and the integration of new tools, including long-acting injectable prevention technologies in prevention programs for those in need; 4. Advance core components of the implementation science agenda across the HIV prevention-to-care cascade in the COVID-19 era, including aspects of integration and approaches for meaningful community engagement and resourcing health systems; 5. Address HIV vulnerability and determinants of disease progression among key and marginalized populations, including novel interventions and implementation science to reduce stigma and discrimination, including intersectional stigmas of HIV, other diseases, homophobia, transphobia, and ethnic and racial disparities. The scientific program will consist of four tracks: Track A ? Basic Science; Track B ? Clinical Science; Track C ? Prevention Science; and Track D ? Social, Behavioral, and Implementation Science. Cross-cutting aspects will be covered in plenary talks that also connect the scientific tracks with community and leadership perspectives, and bridging sessions will cut across at least two of the tracks to provide opportunities for multi-disciplinary dialogues. The participation of young researchers, basic scientists and researchers in related fields such as non- communicable diseases will be strengthened by active solicitation of relevant science and the provision of specific financial support, in addition to increased remote-access options.