Access to Rare Indications Act of 2021 This bill provides for coverage under the Medicare prescription drug benefit, Medicaid, and private health insurance of certain drugs that are used to treat rare diseases or conditions (i.e., diseases or conditions that affect 200,000 or fewer individuals). Such drugs must be supported by peer-reviewed research or medical experts and must not have been reviewed unfavorably in specified compendia or used in a way that conflicts with approved labels.