Medicare Prescription Drug Savings and Choice Act of 2019 This bill requires the Centers for Medicare & Medicaid Services (CMS) to establish at least one prescription drug plan that is operated by Medicare. Among other things, the plan must (1) serve the entire United States; and (2) be the default plan for enrollees under the Medicare prescription drug benefit, unless the enrollee chooses another plan. Additionally, the CMS must negotiate prices for prescription drugs that are covered under the plan and, if appropriate, encourage the use of more affordable therapeutic equivalents. (Currently, the CMS is prohibited from negotiating the prices of covered drugs under the Medicare prescription drug benefit.) The Agency for Healthcare Research and Quality must assess the clinical benefits of drugs and make recommendations to the CMS regarding price negotiations, based on specified information (e.g., comparable international prices).