Without a vaccination program, by the end of June 2021 there would have been approximately 279,000 additional deaths and up to 1.25 million additional hospitalizations. If the U.S. had achieved only half the actual pace of vaccination, there would have been nearly 121,000 additional deaths and more than 450,000 additional hospitalizations. If there had been no vaccination program, daily deaths from COVID-19 potentially would have jumped to nearly 4,500 deaths per day during a second “2021 spring surge” — eclipsing the observed daily peak of 4,000 during the first 2021 winter surge.