A single-payer universal health care system could cover every American, save more than 100,000 lives a year, and still cost $1 trillion less than the system it would replace, according to a new preprint study led by researchers at the Yale School of Public Health.

For the study, which has not yet been peer reviewed, the researchers modeled what would happen if the United States adopted a national public insurance program like the one proposed in the Medicare for All Act. Using 2024 spending, insurance coverage, and mortality data, they estimate that the universal coverage would reduce annual health expenditures by $1.04 trillion, or nearly 20% — even after accounting for the additional care that uninsured and underinsured people would receive.