Background
It has been two years since the first COVID-19 vaccine was given to a patient in the United States. Since then, the U.S. has administered more than 655 million doses — 80 percent of the population has received at least one dose — with the cumulative effect of preventing more than 18 million additional hospitalizations and more than 3 million additional deaths. The swift development of the vaccine, emergency authorization to distribute widely, and rapid rollout have been instrumental in curbing hospitalization and death, while mitigating socioeconomic repercussions of the pandemic.
As more transmissible and immune-evasive variants have emerged over the past two years, the U.S. has responded by deploying additional doses and variant-specific boosters. The Omicron variants caused the largest wave of infections during the pandemic. COVID-19 monovalent vaccines available at the time were not as efficacious against the variant as bivalent boosters introduced later, but the wave would have been more devastating in the absence of vaccination.
As we mark the second anniversary of the U.S. COVID-19 vaccination campaign, understanding the impact of vaccines on reducing disease burden is needed to inform future, evidence-based actions. We therefore used a computer model of disease transmission to estimate hospitalizations and deaths averted through the end of November 2022. The model incorporates the age-stratified demographics, risk factors, and immunological dynamics of infection and vaccination. We simulated this model to compare the observed pandemic trajectory to a counterfactual scenario without a vaccination program. See “How We Conducted This Study” at the end of this post for further details on our methods.
Findings
From December 2020 through November 2022, we estimate that the COVID-19 vaccination program in the U.S. prevented more than 18.5 million additional hospitalizations and 3.2 million additional deaths. Without vaccination, there would have been nearly 120 million more COVID-19 infections. The vaccination program also saved the U.S. $1.15 trillion (Credible Interval: $1.10 trillion–$1.19 trillion) (data not shown) in medical costs that would otherwise have been incurred.