Biosecurity Information Optimization for Defense Act of 2021 This bill directs the President to establish a cabinet-level interagency forum to be known as the National Biodefense Directorate. The directorate must develop a (1) national biodefense strategy and implementation plan, and (2) national strategy for combating public health misinformation and disinformation that threatens the national security and associated implementation plan. The directorate must submit to the National Security Council and Congress a report including the National Biodefense Strategy and associated implementation plans. The Government Accountability Office must review the report and submit to Congress a report that identifies gaps in such strategies and plans and that makes recommendations to address such gaps.