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COVID-19-Associated Hospitalizations Among Vaccinated and Unvaccinated Adults 18 Years or Older in 13 US States, January 2021 to April 2022

Educational Objective
To identify the key insights or developments described in this article
1 Credit CME
Key Points

Question  How do COVID-19–associated hospitalization rates compare among adults who are unvaccinated and vaccinated, and what are the risk factors for hospitalization for COVID-19 among vaccinated persons?

Findings  In this cross-sectional study of US adults hospitalized with COVID-19 during January 2022 to April 2022 (during Omicron variant predominance), COVID-19-associated hospitalization rates were 10.5 times higher in unvaccinated persons and 2.5 times higher in vaccinated persons with no booster dose, respectively, compared with those who had received a booster dose. Compared with unvaccinated hospitalized persons, vaccinated hospitalized persons were more likely to be older and have more underlying medical conditions.

Meaning  The study results suggest that COVID-19 vaccines are strongly associated with prevention of serious COVID-19 illness.

Abstract

Importance  Understanding risk factors for hospitalization in vaccinated persons and the association of COVID-19 vaccines with hospitalization rates is critical for public health efforts to control COVID-19.

Objective  To determine characteristics of COVID-19–associated hospitalizations among vaccinated persons and comparative hospitalization rates in unvaccinated and vaccinated persons.

Design, Setting, and Participants  From January 1, 2021, to April 30, 2022, patients 18 years or older with laboratory-confirmed SARS-CoV-2 infection were identified from more than 250 hospitals in the population-based COVID-19–Associated Hospitalization Surveillance Network. State immunization information system data were linked to cases, and the vaccination coverage data of the defined catchment population were used to compare hospitalization rates in unvaccinated and vaccinated individuals. Vaccinated and unvaccinated patient characteristics were compared in a representative sample with detailed medical record review; unweighted case counts and weighted percentages were calculated.

Exposures  Laboratory-confirmed COVID-19–associated hospitalization, defined as a positive SARS-CoV-2 test result within 14 days before or during hospitalization.

Main Outcomes and Measures  COVID-19–associated hospitalization rates among vaccinated vs unvaccinated persons and factors associated with COVID-19–associated hospitalization in vaccinated persons were assessed.

Results  Using representative data from 192 509 hospitalizations (see Table 1 for demographic information), monthly COVID-19–associated hospitalization rates ranged from 3.5 times to 17.7 times higher in unvaccinated persons than vaccinated persons regardless of booster dose status. From January to April 2022, when the Omicron variant was predominant, hospitalization rates were 10.5 times higher in unvaccinated persons and 2.5 times higher in vaccinated persons with no booster dose, respectively, compared with those who had received a booster dose. Among sampled cases, vaccinated hospitalized patients with COVID-19 were older than those who were unvaccinated (median [IQR] age, 70 [58-80] years vs 58 [46-70] years, respectively; P < .001) and more likely to have 3 or more underlying medical conditions (1926 [77.8%] vs 4124 [51.6%], respectively; P < .001).

Conclusions and Relevance  In this cross-sectional study of US adults hospitalized with COVID-19, unvaccinated adults were more likely to be hospitalized compared with vaccinated adults; hospitalization rates were lowest in those who had received a booster dose. Hospitalized vaccinated persons were older and more likely to have 3 or more underlying medical conditions and be long-term care facility residents compared with hospitalized unvaccinated persons. The study results suggest that clinicians and public health practitioners should continue to promote vaccination with all recommended doses for eligible persons.

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Article Information

Accepted for Publication: August 4, 2022.

Published Online: September 8, 2022. doi:10.1001/jamainternmed.2022.4299

Corresponding Author: Fiona Havers, MD, MHS, 1600 Clifton Rd, US Centers for Disease Control and PrevenMS H24-6, Atlanta, GA 30329 (fhavers@cdc.gov).

Open Access: This is an open access article distributed under the terms of the CC-BY License. © 2022 Havers FP et al. JAMA Internal Medicine.

Author Contributions: Dr Havers had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

Concept and design: Havers, Pham, Milucky, Meek, Lynfield, Como-Sabetti, Talbot.

Acquisition, analysis, or interpretation of data: All authors.

Drafting of the manuscript: Havers, Pham, Billing, Murthy, McMorrow.

Critical revision of the manuscript for important intellectual content: Pham, Taylor, Whitaker, Patel, Anglin, Kambhampati, Milucky, Zell, Moline, Chai, Daily Kirley, Alden, Armistead, Yousey-Hindes, Meek, Openo, Anderson, Reeg, Kohrman, Lynfield, Como-Sabetti, Davis, Cline, Muse, Barney, Bushey, Felsen, Shiltz, Sutton, Abdullah, Talbot, Schaffner, Hill, George, Hall, Bialek, Murthy, Patel Murthy, McMorrow.

Statistical analysis: Pham, Whitaker, Patel, Milucky, Moline, Como-Sabetti.

Obtained funding: Havers, Meek, Schaffner, McMorrow.

Administrative, technical, or material support: Havers, Pham, Taylor, Anglin, Kambhampati, Milucky, Zell, Alden, Meek, Openo, Anderson, Lynfield, Como-Sabetti, Barney, Billing, Sutton, Schaffner, Hill, Hall, Murthy, Patel Murthy, McMorrow.

Supervision: Havers, Meek, Anderson, Como-Sabetti, Sutton, Talbot, Schaffner, Hill, Hall, Bialek, McMorrow.

Other - data collection and reporting: Bushey.

Other - contribution of site specific data collection information: Daily Kirley.

Other - reviewed the draft and provided comments: Abdullah.

Conflict of Interest Disclosures: Drs Yousey-Hindes, Lynfield, Sutton, Talbot, and Meek reported grants from US Centers for Disease Control and Prevention (CDC) during the conduct of the study. Dr Anderson reported grants from Pfizer, Sanofi, GSK, Janssen, MedImmune, Regeneron, PaxVax, Micron, and Merck as well as personal fees from Moderna, Pfizer, Sanofi, GSK, Janssen, Medscape, Kentucky BioProcessing Inc, and WCG and ACI outside the submitted work; additionally, his institution has also received funding from the National Institutes of Health to conduct clinical trials of COVID-19 vaccines. Drs Reeg and Kohrman reported grants from the Michigan Department of Health and Human Services during the conduct of the study. Drs Billing and Shiltz reported grants from the Council of State and Territorial Epidemiologists (CTSTE) and the CDC Dr Schaffner reported grants from CDC during the conduct of the study as well as personal fees from VBI Vaccines outside the submitted work. Drs Hill and George reported grants from CSTE during the conduct of the study. No other disclosures were reported.

Funding/Support: This work was supported by the CDC through an Emerging Infections Program cooperative agreement (grant CK17-1701) and through a CSTE cooperative agreement (grant NU38OT000297-02-00).

Role of the Funder/Sponsor: CDC was involved with the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.

Disclaimer: The findings and conclusions in this report are those of the authors and do not necessarily represent the views of the CDC.

Additional Contributions: The following people were involved in the collection and management of study data and received funding from CDC for these activities: Roxanne Archer, MPH, Susan Brooks, MPH, Monica Napoles, BS, Jeremy Roland, MPH, Tiffany Tsukuda, MPH, California Emerging Infections Program; Arthur Reingold, MD, University of California, Berkeley; Rachel Herlihy, MD, MPH, Breanna Kawasaki, MPH, Sarah McLafferty, MPH, Millen Tsegaye, MHA Jordan Surgnier, MPH, Colorado Department of Public Health and Environment; Ann Basting, BS, Tessa Carter, MPH, Maria Correa, MPH, Daewi Kim, MBS, Carol Lyons, MPH, Amber Maslar, MPA, Julie Plano, MS, Hazhia Sorosindi, BS, Connecticut Emerging Infections Program, Yale School of Public Health; Katelyn Ward, MPH, Georgia Emerging Infections Program, Georgia Department of Public Health, Division of Infectious Diseases, Emory University School of Medicine; Marina Bruck, MPH, Rayna Ceasar, BS, Gracie Chambers, BS, Taylor Eisenstein, MPH, Emily Fawcett, MPH, Asmith Joseph, MPH, Grayson Kallas, MPH, Stephanie Lehman, BSN, RN, Jana Manning, MPH, Hope Wilson, MPH, Johanna Hernandez, MPH, Sabrina Hendrick, MPH, Annabel Patterson, MPH, Allison Roebling, DVM, MPH, Chandler Surell, MPH, Georgia Emerging Infections Program, Georgia Department of Public Health, Veterans Affairs Medical Center, Foundation for Atlanta Veterans Education and Research; Sue Kim, MPH, Val Tellez Nunez, MPH, Chloe Brown, MPH, Jim Collins, MPH, Justin Henderson, MPH, Shannon Johnson, MPH, Lauren Leegwater, MPH, Sierra Peguies-Khan, MPH, Michigan Department of Health and Human Services; Stephanie Meyer, MPH, Keeley Morris, MPH, Aaron Bieringer, BS, Erica Bye, MPH, Richard Danila, PhD, MPH, Corinne Holtzman, MPH, Sydney Kuramoto, MPH, Miriam Muscoplat, MPH, Kayla Bilski, MPH, Amanda Markelz, MPH, Margaret Roddy, MPH, Amy Saupe, MPH, Kristin Sweet, PhD, MPH, Minnesota Department of Health; Marianne Murphy, Murtada Khalifa, MBBS, Yassir Talha, MBBS, CDC Foundation, New Mexico Department of Health; Florent Nkouaga, MA, Melissa Judson, Sunshine Martinez, Jasmyn Sanchez, Susan L. Ropp, PhD, Chad Smelser, MD, Daniel M. Sosin, MD, MPH, New Mexico Department of Health; Dominic Rudin, BS, Kathy M. Angeles, MPH, Melissa Christian, MPH, Nancy Eisenberg, MPH, Emily B. Hancock, MS, Sarah A. Khanlian, MPH, Sarah Lathrop, DVM, PhD, Wickliffe Omondi, MPH, Mayvilynne Poblete, MA, MPH, Yadira Salazar-Sánchez, MPH, Sarah Shrum Davis, MPH, Chelsea McMullen, MSc-GH, New Mexico Emerging Infections Program; Nancy Spina, MPH, Kerianne Engesser, MPH, Suzanne McGuire, MPH, Adam Rowe, BA, New York State Department of Health; Nancy M. Bennett, MD, MS, Virginia Cafferky, BS, Maria Gaitán, BS, Christine Long, MPH, Thomas Peer, MPH, Kevin Popham, MPH, University of Rochester School of Medicine and Dentistry; Kylie Seeley, MD, MPH, Oregon Health & Science University School of Medicine; Sam Hawkins, MPH, Ama Owusu-Dommey, MPH, Emily Youngers, MPH, Breanna McArdle, MPH, Public Health Division; Oregon Health Authority; Tiffanie Markus, PhD, Kathy Billings, MPH, Katie Dyer, Anise Elie, MPH, BSN, RN, Karen Leib, BSN, RN, Terri McMinn, Danielle Ndi, MPH, Manideepthi Pemmaraju, MBBS, MPH, John Ujwok, MPH, Vanderbilt University Medical Center; Amanda Carter, BS, Ryan Chatelain, MPH, Andrew Haraghey, BS, Laine McCullough, MPH, Jacob Ortega, MPH, Andrea Price, LPN, Tyler Riedesel, MPH, Caitlin Shaw, BS, Melanie Crossland, MPH, Ashley Swain, Salt Lake County Health Department; Keegan McCaffrey, BS, Utah Department of Health; Kelly Oakeson, PhD, and Alessandro Rossi, PhD, Utah Public Health Laboratory. In addition, Li Deng, PhD, CDC, contributed statistical advice, and Hannah E. Fast, MPH, CDC, assisted with vaccination coverage data. Neither received additional funding for these activities.

References
1.
US Centers for Diseases Control and Prevention. CDC COVID data tracker. Accessed May 15, 2022. https://covid.cdc.gov/covid-data-tracker/#vaccinations_vacc-total-admin-rate-total
2.
Mbaeyi  S , Oliver  SE , Collins  JP ,  et al.  The Advisory Committee on Immunization Practices’ interim recommendations for additional primary and booster doses of COVID-19 vaccines—United States, 2021.   MMWR Morb Mortal Wkly Rep. 2021;70(44):1545-1552. doi:10.15585/mmwr.mm7044e2 PubMedGoogle ScholarCrossref
3.
Butt  AA , Talisa  VB , Shaikh  OS , Omer  SB , Mayr  FB .  Relative vaccine effectiveness of a SARS-CoV-2 mRNA vaccine booster dose against the Omicron variant.   Clin Infect Dis. Published online May 3, 2022. PubMedGoogle Scholar
4.
Adams  K , Rhoads  JP , Surie  D ,  et al.  Vaccine effectiveness of primary series and booster doses against Omicron variant COVID-19–associated hospitalization in the United States.   medRxiv. Posted online June 14, 2022. . doi:10.1101/2022.06.09.22276228Google Scholar
5.
Bajema  KL , Dahl  RM , Prill  MM ,  et al; Surveillance Platform for Enteric and Respiratory Infectious Organisms at the VA COVID-19 Surveillance Group.  Effectiveness of COVID-19 mRNA vaccines against COVID-19–associated hospitalization—five Veterans Affairs medical centers, United States, February 1-August 6, 2021.   MMWR Morb Mortal Wkly Rep. 2021;70(37):1294-1299. doi:10.15585/mmwr.mm7037e3 PubMedGoogle ScholarCrossref
6.
Thompson  MG , Burgess  JL , Naleway  AL ,  et al.  Prevention and attenuation of Covid-19 with the BNT162b2 and mRNA-1273 vaccines.   N Engl J Med. 2021;385(4):320-329. doi:10.1056/NEJMoa2107058 PubMedGoogle ScholarCrossref
7.
Yek  C , Warner  S , Wiltz  JL ,  et al.  Risk factors for severe COVID-19 outcomes among persons aged ≥18 years who completed a primary COVID-19 vaccination series—465 health care facilities, United States, December 2020-October 2021.   MMWR Morb Mortal Wkly Rep. 2022;71(1):19-25. doi:10.15585/mmwr.mm7101a4 PubMedGoogle ScholarCrossref
8.
US Centers for Disease Control and Prevention. CDC data tracker: variant proportions. Accessed June 2, 2022. https://covid.cdc.gov/covid-data-tracker/#variant-proportions
9.
Havers  FP , Patel  K , Whitaker  M ,  et al; COVID-NET Surveillance Team.  Laboratory-confirmed COVID-19–associated hospitalizations among adults during SARS-CoV-2 Omicron BA.2 variant predominance—COVID-19–Associated Hospitalization Surveillance Network, 14 states, June 20, 2021–May 31, 2022.   MMWR Morb Mortal Wkly Rep. 2022;71(34):1085-1091. doi:10.15585/mmwr.mm7134a3PubMedGoogle ScholarCrossref
10.
Taylor  CA , Whitaker  M , Anglin  O ,  et al; COVID-NET Surveillance Team.  COVID-19–associated hospitalizations among adults during SARS-CoV-2 Delta and Omicron variant predominance, by race/ethnicity and vaccination status—COVID-NET, 14 states, July 2021-January 2022.   MMWR Morb Mortal Wkly Rep. 2022;71(12):466-473. doi:10.15585/mmwr.mm7112e2 PubMedGoogle ScholarCrossref
11.
US Centers for Disease Control and Prevention. Rates of laboratory-confirmed COVID-19 hospitalizations by vaccination status. Accessed May 31, 2022. https://covid.cdc.gov/covid-data-tracker/#covidnet-hospitalizations-vaccination
12.
Garg  S , Kim  L , Whitaker  M ,  et al.  Hospitalization rates and characteristics of patients hospitalized with laboratory-confirmed coronavirus disease 2019—COVID-NET, 14 states, March 1-30, 2020.   MMWR Morb Mortal Wkly Rep. 2020;69(15):458-464. doi:10.15585/mmwr.mm6915e3 PubMedGoogle ScholarCrossref
13.
National Archives. Electronic Code of Federal Regulations (eCFR). Accessed January 4, 2022. https://www.ecfr.gov/
14.
Garg  S , Patel  K , Pham  H ,  et al.  Clinical trends among U.S. adults hospitalized with COVID-19, March to December 2020 : a cross-sectional study.   Ann Intern Med. 2021;174(10):1409-1419. doi:10.7326/M21-1991 PubMedGoogle ScholarCrossref
15.
Moline  HL , Whitaker  M , Deng  L ,  et al.  Effectiveness of COVID-19 vaccines in preventing hospitalization among adults aged ≥65 years—COVID-NET, 13 states, February-April 2021.   MMWR Morb Mortal Wkly Rep. 2021;70(32):1088-1093. doi:10.15585/mmwr.mm7032e3 PubMedGoogle ScholarCrossref
16.
Marks  KJ , Whitaker  M , Anglin  O ,  et al; COVID-NET Surveillance Team.  Hospitalizations of children and adolescents with laboratory-confirmed COVID-19—COVID-NET, 14 states, July 2021-January 2022.   MMWR Morb Mortal Wkly Rep. 2022;71(7):271-278. doi:10.15585/mmwr.mm7107e4 PubMedGoogle ScholarCrossref
17.
Parsons  LS . Reducing bias in a propensity score matched-pair sample using greedy matching techniques. Accessed March 13, 2022. http://www2.sas.com/proceedings/sugi26/p214-26.pdf
18.
Karabon  P . Applying propensity score methods to complex survey data using PROC PSMATCH. Accessed March 13, 2022. https://www.sas.com/content/dam/SAS/support/en/sas-global-forum-proceedings/2019/3634-2019.pdf
19.
US Centers for Disease Control and Prevention. U.S. Census populations with bridged race categories. Accessed February 3, 2022. https://www.cdc.gov/nchs/nvss/bridged_race.htm
20.
King County Department of Health. Estimating COVID incidence, hospitalization, and death rates among people who are not fully vaccinated. King County. Accessed March 16, 2022. https://kingcounty.gov/depts/health/covid-19/data/~/media/depts/health/communicable-diseases/documents/C19/calculation-method-technical-appendix.ashx
21.
Havers  FP , Pham  H , Taylor  CA ,  et al.  COVID-19-associated hospitalizations among vaccinated and unvaccinated adults ≥18 years—COVID-NET, 13 states, January 1-July 24, 2021.   medRxiv. Posted August 29, 2021. . doi:10.1101/2021.08.27.21262356Google Scholar
22.
Wolter  KM .  Introduction to Variance Estimation. 2nd ed. Springer-Verlag;2007.
23.
Tenforde  MW , Patel  MM , Ginde  AA ,  et al; Influenza and Other Viruses in the Acutely Ill Network.  Effectiveness of SARS-CoV-2 mRNA vaccines for preventing Covid-19 Hospitalizations in the United States.   medRxiv. Posted July 8, 2021. doi:10.1101/2021.07.08.21259776 PubMedGoogle Scholar
24.
Brosh-Nissimov  T , Orenbuch-Harroch  E , Chowers  M ,  et al.  BNT162b2 vaccine breakthrough: clinical characteristics of 152 fully vaccinated hospitalized COVID-19 patients in Israel.   Clin Microbiol Infect. 2021;27(11):1652-1657. doi:10.1016/j.cmi.2021.06.036 PubMedGoogle ScholarCrossref
25.
Tenforde  MW , Self  WH , Adams  K ,  et al; Influenza and Other Viruses in the Acutely Ill Network.  Association between mRNA vaccination and COVID-19 hospitalization and disease severity.   JAMA. 2021;326(20):2043-2054. doi:10.1001/jama.2021.19499 PubMedGoogle ScholarCrossref
26.
US Centers for Disease Control and Prevention. Stay up to date with your COVID-19 vaccines. Accessed June 24, 2022. https://www.cdc.gov/coronavirus/2019-ncov/vaccines/stay-up-to-date.html
27.
US Centers for Disease Control and Prevention. Underlying medical conditions associated with higher risk for severe COVID-19: information for healthcare professionals. Accessed March 15, 2022. https://www.cdc.gov/coronavirus/2019-ncov/hcp/clinical-care/underlyingconditions.html
28.
Gottlieb  RL , Juneja  K , Hill  JA .  Outpatient remdesivir to prevent progression to severe Covid-19—reply.   N Engl J Med. 2022;386(11):1094. doi:10.1056/NEJMc2200591 PubMedGoogle ScholarCrossref
29.
Hammond  J , Leister-Tebbe  H , Gardner  A ,  et al; EPIC-HR Investigators.  Oral nirmatrelvir for high-risk, nonhospitalized adults with Covid-19.   N Engl J Med. 2022;386(15):1397-1408. doi:10.1056/NEJMoa2118542 PubMedGoogle ScholarCrossref
30.
National Institutes of Health. COVID-19 treatment guidelines. Accessed May 31, 2022. https://www.covid19treatmentguidelines.nih.gov/
31.
National Institutes of Health. Prioritization of anti–SARS-CoV-2 therapies for the treatment and prevention of COVID-19 when there are logistical or supply constraints. Accessed May 13, 2022 https://www.covid19treatmentguidelines.nih.gov/overview/prioritization-of-therapeutics/
32.
US Centers for Disease Control and Prevention. Demographic characteristics of people receiving COVID-19 vaccinations in the United States. Accessed May 2, 2022. https://covid.cdc.gov/covid-data-tracker/#vaccination-demographic
33.
Acosta  AM , Garg  S , Pham  H ,  et al.  Racial and ethnic disparities in rates of COVID-19–associated hospitalization, intensive care unit admission, and in-hospital death in the United States from March 2020 to February 2021.   JAMA Netw Open. 2021;4(10):e2130479. doi:10.1001/jamanetworkopen.2021.30479 PubMedGoogle ScholarCrossref
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