Rec. 1: The DoD OIG recommended that the Defense Health Agency Director, with input from the Military Departments, the National Guard Bureau, and other stakeholders, review challenges and difficulties encountered during the distribution and administration of the coronavirus disease-2019 vaccine, compile a report detailing the issues, and determine if corrective actions are necessary to support future pandemic response planning. At a minimum, the review should include the following challenges and difficulties: * Determining the vaccine-eligible population at each military treatment facility; * Reporting vaccine administration data; * Communicating vaccination tier eligibility; * Coordinating tier movement between military treatment facilities; * Allocating vaccine to overseas locations; and * Vaccinating local nationals who work alongside U.S. personnel at overseas locations.