Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2023 Apr 3;6(4):e239050.
doi: 10.1001/jamanetworkopen.2023.9050.

Trends in Severe Outcomes Among Adult and Pediatric Patients Hospitalized With COVID-19 in the Canadian Nosocomial Infection Surveillance Program, March 2020 to May 2022

Robyn Mitchell  1 , Joelle Cayen  1 , Nisha Thampi  2 , Charles Frenette  3 , Jessica Bartoszko  1 , Kelly Baekyung Choi  1 , Jeannette L Comeau  4 , John Conly  5 , Chelsey Ellis  6 , Jennifer Ellison  7 , John Embil  8 , Gerald Evans  9 , Lynn Johnston  10 , Jennie Johnstone  11 , Kevin C Katz  12 , Pamela Kibsey  13 , Bonita Lee  14 , Marie-Astrid Lefebvre  15 , Yves Longtin  16 , Allison McGeer  11 , Dominik Mertz  17 , Jessica Minion  18 , Wallis Rudnick  1 , Anada Silva  1 , Stephanie W Smith  19 , Jocelyn A Srigley  20 , Kathryn N Suh  21 , Jen Tomlinson  8 , Alice Wong  22 , Linda Pelude  1
Affiliations

Trends in Severe Outcomes Among Adult and Pediatric Patients Hospitalized With COVID-19 in the Canadian Nosocomial Infection Surveillance Program, March 2020 to May 2022

Robyn Mitchell et al. JAMA Netw Open. .

Erratum in

  • Error in Byline, Affiliations, and Contributions.
    [No authors listed] [No authors listed] JAMA Netw Open. 2023 May 1;6(5):e2317468. doi: 10.1001/jamanetworkopen.2023.17468. JAMA Netw Open. 2023. PMID: 37219910 Free PMC article. No abstract available.
  • Error in Methods.
    [No authors listed] [No authors listed] JAMA Netw Open. 2023 Aug 1;6(8):e2329475. doi: 10.1001/jamanetworkopen.2023.29475. JAMA Netw Open. 2023. PMID: 37552485 Free PMC article. No abstract available.

Abstract

Importance: Trends in COVID-19 severe outcomes have significant implications for the health care system and are key to informing public health measures. However, data summarizing trends in severe outcomes among patients hospitalized with COVID-19 in Canada are not well described.

Objective: To describe trends in severe outcomes among patients hospitalized with COVID-19 during the first 2 years of the COVID-19 pandemic.

Design, setting, and participants: Active prospective surveillance in this cohort study was conducted from March 15, 2020, to May 28, 2022, at a sentinel network of 155 acute care hospitals across Canada. Participants included adult (aged ≥18 years) and pediatric (aged 0-17 years) patients hospitalized with laboratory-confirmed COVID-19 at a Canadian Nosocomial Infection Surveillance Program (CNISP)-participating hospital.

Exposures: COVID-19 waves, COVID-19 vaccination status, and age group.

Main outcomes and measures: The CNISP collected weekly aggregate data on the following severe outcomes: hospitalization, admission to an intensive care unit (ICU), receipt of mechanical ventilation, receipt of extracorporeal membrane oxygenation, and all-cause in-hospital death.

Results: Among 1 513 065 admissions, the proportion of adult (n = 51 679) and pediatric (n = 4035) patients hospitalized with laboratory-confirmed COVID-19 was highest in waves 5 and 6 of the pandemic compared with waves 1 to 4 (77.3 vs 24.7 per 1000 patient admissions). Despite this, the proportion of patients with positive test results for COVID-19 who were admitted to an ICU, received mechanical ventilation, received extracorporeal membrane oxygenation, and died were each significantly lower in waves 5 and 6 when compared with waves 1 through 4. Admission to the ICU and in-hospital all-cause death rates were significantly higher among those who were unvaccinated against COVID-19 when compared with those who were fully vaccinated (incidence rate ratio, 4.3 and 3.9, respectively) or fully vaccinated with an additional dose (incidence rate ratio, 12.2 and 15.1, respectively).

Conclusions and relevance: The findings of this cohort study of patients hospitalized with laboratory-confirmed COVID-19 suggest that COVID-19 vaccination is important to reduce the burden on the Canadian health care system as well as severe outcomes associated with COVID-19.

PubMed Disclaimer

Conflict of interest statement

Conflict of Interest Disclosures: Dr Conly reported receiving grants from Pfizer Inc provided only to the University of Calgary, the Canadian Institutes of Health Research, the World Health Organization (WHO), and the Synder Institute for Chronic Diseases; receiving accommodation and travel expenses from the Centers for Disease Control and Prevention and bioMérieux outside the submitted work; serving as a member and chair of the WHO Infection Prevention and Control Research and Development Expert Group for COVID-19 and a member of the WHO Health Emergencies Programme Ad-hoc COVID-19 Infection Prevention and Control Guidance Development Group; and serving as a member of the Cochrane Acute Respiratory Infections Working Group. Ms Ellison reported receiving a stipend from the Canadian Nosocomial Infection Surveillance Program (CNISP) for surveillance data submitted by Alberta Health Services during the conduct of the study. Dr Evans reported receiving grant funding from the CNISP during the conduct of the study. Dr Longtin reported receiving grant funding from Summit (Oxford) Limited outside the submitted work. Dr McGeer reported receiving grant funding from the COVID-19 Immunity Task Force, the Canadian Institutes of Health Research, Pfizer Inc, Sanofi Pasteur Inc, and Appili Therapeutics Inc to her institution and honoraria from AstraZeneca, GlaxoSmithKline, Janssen Pharmaceuticals, Medicago Inc, Merck & Co Inc, Moderna Inc, Novavax Inc, and Pfizer Inc for advisory boards, data safety monitoring boards, and webinars outside the submitted work. Dr Minion reported receiving grant funding from Public Health Agency of Canada to her institution for contributing to these surveillance activities during the conduct of the study. Dr Srigley reported receiving grant funding from the COVID-19 Immunity Task Force outside the submitted work. No other disclosures were reported.

Figures

Figure 1.
Figure 1.. Weekly Proportion of Adult and Pediatric Patients Hospitalized With COVID−19, Patients Admitted to an Intensive Care Unit (ICU), and All-Cause In-Hospital Deaths per 1000 Patient Admissions
Events occurred from March 15, 2020, to May 28, 2022. Data were obtained from 64 adult, mixed, and pediatric Canadian Nosocomial Infection Surveillance Program hospitals with age-stratified denominator data. Adults were 18 years or older; pediatric patients, younger than 18 years.
Figure 2.
Figure 2.. Proportion of Severe Outcomes Among Adult Patients Hospitalized With COVID-19 by Wave
Data are from 153 hospitals. ECMO indicates extracorporeal membrane oxygenation; ICU, intensive care unit.
Figure 3.
Figure 3.. Proportion of Severe Outcomes Among Pediatric Patients Hospitalized With COVID-19 by Wave
Data are from 81 hospitals. ICU indicates intensive care unit.
Figure 4.
Figure 4.. Cumulative Age-Standardized Incident Rates of COVID-19–Positive Patients Admitted to the Intensive Care Unit (ICU) and Who Died (In-Hospital, All Causes)
Data are stratified by vaccination status per 1 000 000 population and from 58 hospitals in waves 5 to 6. Denominators were adjusted to reflect that approximately one-third of hospitalized patients in Canada are captured by the Canadian Nosocomial Infection Surveillance Program. Partially vaccinated patients (defined as patients with a symptom onset or specimen collection date that was ≥14 days following receipt of a first dose of a 2-dose COVID-19 vaccine or <14 days after receiving a second dose) were excluded from these analyses. Vaccine coverage data are from the Public Health Agency of Canada.
See this image and copyright information in PMC

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

References

    1. Public Health Agency of Canada . COVID-19 signs, symptoms and severity of disease: a clinician guide. Updated June 1, 2022. Accessed March 23, 2022. https://www.canada.ca/en/public-health/services/diseases/2019-novel-coro...
    1. Danza P, Koo TH, Haddix M, et al. . SARS-CoV-2 infection and hospitalization among adults aged ≥18 years, by vaccination status, before and during SARS-CoV-2 B.1.1.529 (Omicron) variant predominance—Los Angeles County, California, November 7, 2021–January 8, 2022. MMWR Morb Mortal Wkly Rep. 2022;71(5):177-181. doi:10.15585/mmwr.mm7105e1 - DOI - PMC - PubMed
    1. Iuliano AD, Brunkard JM, Boehmer TK, et al. . Trends in disease severity and health care utilization during the early Omicron variant period compared with previous SARS-CoV-2 high transmission periods—United States, December 2020–January 2022. MMWR Morb Mortal Wkly Rep. 2022;71(4):146-152. doi:10.15585/mmwr.mm7104e4 - DOI - PMC - PubMed
    1. León TM, Dorabawila V, Nelson L, et al. . COVID-19 cases and hospitalizations by COVID-19 vaccination status and previous COVID-19 diagnosis—California and New York, May–November 2021. MMWR Morb Mortal Wkly Rep. 2022;71(4):125-131. doi:10.15585/mmwr.mm7104e1 - DOI - PMC - PubMed
    1. Centers for Disease Control and Prevention . Science brief: SARS-CoV-2 infection-induced and vaccine-induced immunity. Updated October 29, 2021. Accessed May 26, 2022. https://www.cdc.gov/coronavirus/2019-ncov/science/science-briefs/vaccine... - PubMed

Substances