Improving Low-Income Access to Prescription Drugs Act of 2019 This bill provides statutory authority for the Centers for Medicare & Medicaid Services transition program under the Medicare prescription drug benefit for limited-income, newly eligible individuals (i.e., individuals who are eligible for subsidies and have not yet enrolled in, or whose coverage has not yet taken effect under, a Medicare or Medicare Advantage prescription drug plan). The program's coverage provides immediate access to covered drugs at the point of sale as soon as the individual becomes eligible for subsidies; coverage also applies retroactively for dual eligible individuals and for individuals who receive benefits under the Supplemental Security Income program.