An age-stratified agent-based model of COVID-19 was used to simulate outbreaks in states within two U. S. regions. The northeastern region consisted of Connecticut, Massachusetts, Maine, New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island and Vermont. The southern region consisted of Alabama, Arkansas, Delaware, District of Columbia, Florida, Georgia, Kentucky, Louisiana, Maryland, Mississippi, North Carolina, Oklahoma, South Carolina, Tennessee, Texas, Virginia and West Virginia. The model was calibrated using reported incidence of COVID-19 in each state from October 1, 2020 to August 31, 2021. It then projected the number of infections, hospitalizations, and deaths that would be averted between September 2021 and the end of March 2022, if states increased their daily vaccination rate.