Estimating COVID-19 associated hospitalizations, ICU admissions, and in-hospital deaths averted in the United States by 2023-2024 COVID-19 vaccination: A conditional probability, causal inference, and multiplier-based approach.

COVID-19-associated hospitalizations, ICU admissions, and in-hospital deaths averted from 2023 to 2024 COVID-19 vaccination from the weeks of October 1, 2023, through April 21, 2024, were estimated via a novel multiplier model that utilized causal inference, conditional probabilities of hospitalization, and correlations between data elements in Monte Carlo simulations. Median COVID-19-associated hospitalizations averted were 68,315 (95 % uncertainty interval [UI] 42,831-97,984), ICU admissions averted were 13,108 (95 % UI 4459-25,042), and in-hospital deaths averted were 5301 (95 % UI 101-14,230). Averted COVID-19-associated burden was highest in adults aged 65 years and older (hospitalizations averted 57,665, 95 % UI 35,442-84,006; ICU admissions averted 10,878, 95 % UI 3104-21,591; in-hospital deaths averted 4779, 95 % UI 0-13,132). Expanding the analytic period to comprise the weeks of September 24, 2023, through August 11, 2024, resulted in 107,197 COVID-19-associated hospitalizations averted (95 % UI 80,692-137,643), 18,292 COVID-19-associated ICU admissions averted (95 % UI 10,062-28,436), and 6749 COVID-19-associated in-hospital deaths averted (95 % UI 2077-13,557). Older adults had the highest COVID-19-associated averted burden and potential to reduce burden further through increased vaccine coverage. 2023-2024 COVID-19 vaccinations reduced the burden of COVID-19-associated severe disease.