Changing Severity and Epidemiology of Adults Hospitalized with Coronavirus Disease 2019 (COVID-19) in the United States after Introduction of COVID-19 Vaccines, March 2021-August 2022

Noah Kojima, Katherine Adams, Wesley H. Self, Manjusha Gaglani, Tresa McNeal, Shekhar Ghamande, Jay S. Steingrub, Nathan I. Shapiro, Abhijit Duggal, Laurence W. Busse, Matthew E. Prekker, Ithan D. Peltan, Samuel M. Brown, David N. Hager, Harith Ali, Michelle N. Gong, Amira Mohamed, Matthew C. Exline, Akram Khan, Jennifer G. WilsonNida Qadir, Steven Y. Chang, Adit A. Ginde, Cori A. Withers, Nicholas M. Mohr, Christopher Mallow, Emily T. Martin, Adam S. Lauring, Nicholas J. Johnson, Jonathan D. Casey, William B. Stubblefield, Kevin W. Gibbs, Jennie H. Kwon, Adrienne Baughman, James D. Chappell, Kimberly W. Hart, Ian D. Jones, Jillian P. Rhoads, Sydney A. Swan, Kelsey N. Womack, Yuwei Zhu, Diya Surie, Meredith L. McMorrow, Manish M. Patel, Mark W. Tenforde

Research output: Contribution to journalArticlepeer-review

14 Scopus citations


Introduction: Understanding the changing epidemiology of adults hospitalized with coronavirus disease 2019 (COVID-19) informs research priorities and public health policies. Methods: Among adults (≥18 years) hospitalized with laboratory-confirmed, acute COVID-19 between 11 March 2021, and 31 August 2022 at 21 hospitals in 18 states, those hospitalized during the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron-predominant period (BA.1, BA.2, BA.4/BA.5) were compared to those from earlier Alpha- and Delta-predominant periods. Demographic characteristics, biomarkers within 24 hours of admission, and outcomes, including oxygen support and death, were assessed. Results: Among 9825 patients, median (interquartile range [IQR]) age was 60 years (47-72), 47% were women, and 21% non-Hispanic Black. From the Alpha-predominant period (Mar-Jul 2021; N = 1312) to the Omicron BA.4/BA.5 sublineage-predominant period (Jun-Aug 2022; N = 1307): the percentage of patients who had ≥4 categories of underlying medical conditions increased from 11% to 21%; those vaccinated with at least a primary COVID-19 vaccine series increased from 7% to 67%; those ≥75 years old increased from 11% to 33%; those who did not receive any supplemental oxygen increased from 18% to 42%. Median (IQR) highest C-reactive protein and D-dimer concentration decreased from 42.0 mg/L (9.9-122.0) to 11.5 mg/L (2.7-42.8) and 3.1 mcg/mL (0.8-640.0) to 1.0 mcg/mL (0.5-2.2), respectively. In-hospital death peaked at 12% in the Delta-predominant period and declined to 4% during the BA.4/BA.5-predominant period. Conclusions: Compared to adults hospitalized during early COVID-19 variant periods, those hospitalized during Omicron-variant COVID-19 were older, had multiple co-morbidities, were more likely to be vaccinated, and less likely to experience severe respiratory disease, systemic inflammation, coagulopathy, and death.

Original languageEnglish
Pages (from-to)547-557
Number of pages11
JournalClinical Infectious Diseases
Issue number4
StatePublished - Aug 15 2023


  • COVID-19
  • SARS-CoV-2
  • death
  • hospitalization
  • severe disease


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