Medical Supplies for Pandemics Act of 2021 This bill requires the Department of Health and Human Services (HHS) to undertake various actions to enhance supply chain elasticity for and maintain domestic reserves of critical medical supplies for the Strategic National Stockpile. Specifically, HHS must increase emergency stocks of supplies, geographically diversify production of supplies, and enter cooperative agreements or partnerships for purposes of supporting domestic production of supplies and replenishing supplies in the stockpile. The department's authority to enter such agreements and partnerships terminates on September 30, 2024.