LAUSR

Background: During March 2020 to September 2022, more than 1 million COVID-19–involved deaths occurred in the United States (1). As described by Shiels and colleagues (2), COVID-19 deaths during March to December 2020 and January to October 2021 were similar. However, COVID-19–involved deaths increased among younger persons and decreased among older adults in 2021 versus 2020 (2), reflecting excess premature mortality from COVID-19. Objective: We endeavored to quantify this downward age shift in COVID-19–involved deaths, which required an ageweighted metric. Unlike the mortality metric, the measure of years of life lost (YLL) (3) offers an indicator of prematuremortality based on the estimated number of years a person would have lived if they had not died prematurely. We therefore sought to estimate YLL associated with leading causes of U.S. death duringmatched 10-month intervals in 2020 and 2021. Methods and Findings: Mortality data from March to December in 2020 and 2021 were obtained from CDCWONDER (Centers for Disease Control and PreventionWide-rangingONline Data for Epidemiologic Research), an integrated system of publicuse data sets spanning public health topics (1). Age-specific standard life expectancies were obtained from the 2017 World Population Prospects and World Health Organization Global Health Estimate, providing frontier-period life expectancy projections for the year 2050 to represent lifespans thought to be achieved by a substantial number of people alive at the time of this analysis (3, 4). Absolute YLL due to cause of death c, in population of age a during interval t were defined as YLL (c, a, t) = D(c, a, t) SLE(a), where D represents the number of deaths and SLE represents standard life expectancy (3). For the 15 leading causes of death, YLL were estimated, comparing March to December 2020 with March to December 2021 to minimize the effects of seasonal variation in mortality on the comparator intervals. Data were analyzed in Python version