In the first 10 months of availability, COVID-19 vaccines prevented around 235,000 deaths and 1.6 million hospitalizations in the U.S. However, by April 2023, 19% of Americans still hadn’t received their first vaccine dose and 65% hadn’t completed all recommended boosters, leading to tens of thousands of preventable deaths. With annual booster recommendations likely, increasing booster uptake is essential to prevent future hospitalizations and deaths.