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
Authors: Kojima Noah , Adams Katherine , Self Wesley H , Gaglani Manjusha , McNeal Tresa , Ghamande Shekhar , Steingrub Jay S , Shapiro Nathan I , Duggal Abhijit , Busse Laurence W , Prekker Matthew E , Peltan Ithan D , Brown Samuel M , Hager David N , Ali Harith , Gong Michelle N , Mohamed Amira , Exline Matthew C , Khan Akram , Wilson Jennifer G , Qadir Nida , Chang Steven Y , Ginde Adit A , Withers Cori A , Mohr Nicholas M , Mallow Christopher , Martin Emily T , Lauring Adam S , Johnson Nicholas J , Casey Jonathan D , Stubblefield William B , Gibbs Kevin W , Kwon Jennie H , Baughman Adrienne , Chappell James D , Hart Kimberly W , Jones Ian D , Rhoads Jillian P , Swan Sydney A , Womack Kelsey N , Zhu Yuwei , Surie Diya , McMorrow Meredith L , Patel Manish M , Tenforde Mark W ,   For the Investigating Respiratory Viruses in the Acutely Ill (IVY) Network, Gaglani Manjusha , McNeal Tresa , Ghamande Shekhar , Calhoun Nicole , Murthy Kempapura , Herrick Judy , McKillop Amanda , Hoffman Eric , Zayed Martha , Smith Michael , Steingrub Jay , Kozikowski Lori-Ann , De Souza Lesley , Ouellette Scott , Shapiro Nathan I , Bolstad Michael , Coviello Brianna , Ciottone Robert , Devilla Arnaldo , Grafals Ana , Higgins Conor , Ottanelli Carlo , Redman Kimberly , Scaffidi Douglas , Weingart Alexander , Surie Diya , McMorrow Meredith , DeCuir Jennifer , Thornburg Natalie , Flannery Brendan , Lewis Nathaniel , Tenforde Mark , Adams Katherine , Patel Manish , Mehkri Omar , Mitchell Megan , Griffith Zachary , Brennan Connery , Ashok Kiran , Poynter Bryan , Duggal Abhijit , Busse Laurence , ten Lohuis Caitlin , Stanley Nicholas , Zhang Sophia , Prekker Matthew , Erickson Heidi , Frosch Anne , Hendrickson Audrey , Caspers Sean , Tordsen Walker , Kaus Olivia , Scharber Tyler , Peltan Ithan , Brown Samuel , Lumpkin Jenna , Smith Cassie , Marshall Hunter , Hager David N , Ali Harith , Rothman Richard E , Gong Michelle , Mohamed Amira , Nair Rahul , Chen Jen-Ting (Tina) , Exline Matthew , Karow Sarah , Robart Emily , Maldonado Paulo Nunes , Khan Maryiam , So Preston , So Madison , Schwartz Elizabeth , Botros Mena , Khan Akram , Hough Catherine L , Jung Haeun , Martinez Jesus , Luong Andrea , Huynh Bao , Ibrahim Habiba , Villanueva-Vargas Cynthia , Villanueva-Vargas Juliana , Quadri Suha , Wilson Jennifer G , Gordon Alexandra June , Perez Cynthia , Lau Lily , Bekiroglu Ismail Hakki , Qadir Nida , Chang Steven , Frankel Trevor , Garner Omai , Chandrasekaran Sukantha , Ginde Adit , Douin David , Jensen Kelly , Huynh David , Steinwand Aimee , Withers Cori , Mohr Nicholas , Zepeski Anne , Nassar Paul , Landers Shannon , Nielsen Karin , Briggs Noble , Fairfield Cathy , Mallow Chris , Rivas Carolina , Martin Emily , Monto Arnold , Lauring Adam , McSpadden E J , Truscon Rachel , Kaniclides Anne , Thomas Lara , Bielak Ramsay , Valvano Weronika Damek , Fong Rebecca , Fitzsimmons William J , Blair Christopher , Gilbert Julie , Baker Leigh , Johnson Nicholas , Srinivasan Vasisht , Crider Christine D , Steinbock Kyle A , Paulsen Thomas C , Anderson Layla A , Self Wesley H , Talbot H Keipp , Grijalva Carlos , Jones Ian , Halasa Natasha , Chappell James , Womack Kelsey , Rhoads Jillian , Baughman Adrienne , Kampe Christy , Johnson Jakea , Hart Kim , Rice Todd , Casey Jonathan , Stubblefield William B , Zhu Yuwei , Short Laura L , Ezzell Lauren J , Whitsett Margaret E , McHenry Rendie E , Hargrave Samarian J , Blair Marcia , Luther Jennifer L , Pulido Claudia Guevara , Peterson Bryan P M , Files D Clark , Gibbs Kevin , LaRose Mary , Landreth Leigha , Hicks Madeline , Parks Lisa , Babcock Hilary , Kwon Jennie , Bongu Jahnavi , McDonald David , Cass Candice , Seiler Sondra , Park David , Hink Tiffany , Wallace Meghan , Burnham Carey-Ann , Arter Olivia G 
Published: May 2023

Abstract

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.