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.

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.

Patients in hospital with laboratory-confirmed COVID-19 in a network of Canadian acute care hospitals, Mar. 1 to Aug. 31, 2020: a descriptive analysis.

BACKGROUND: Information on the epidemiology of patients in hospital with laboratory-confirmed coronavirus disease 2019 (COVID-19) in Canadian acute care hospitals is needed to inform infection prevention and control strategies and public health measures. The aim of this surveillance was to describe the epidemiology of patients in hospital with laboratory-confirmed COVID-19 in a network of Canadian acute care hospitals between Mar. 1 and Aug. 31, 2020. METHODS: Through prospective surveillance, we identified adult and pediatric patients in hospital with laboratory-confirmed COVID-19 using a standard definition between Mar. 1 and Aug. 31, 2020, through the Canadian Nosocomial Infection Surveillance Program (CNISP), a network of 78 hospitals. Patient demographic and clinical characteristics and data on treatment, interventions and outcomes were reviewed and described. RESULTS: As of Aug. 31, 2020, the CNISP had received data for 1906 patients in hospital with COVID-19 in 49 sentinel hospitals in 9 provinces. The majority of patients in hospital with COVID-19 were older (median age 71 yr) and had underlying medical conditions (85.8%). Few children with COVID-19 were admitted to a participating hospital (n = 37, 1.9%). Acquisition of COVID-19 in hospitals was infrequent (6.4% of all cases). A total of 32.8% of patients were admitted from a long-term care facility or retirement home. Health care workers constituted 10.6% of adult patients aged 18-65 years in hospital with COVID-19. Thirty-day attributable mortality was 16.2%. Hospital admission rates peaked in mid-April and were highest in Ontario and Quebec. INTERPRETATION: Surveillance findings indicate that a high proportion of Canadian patients in hospital with COVID-19 during the first 6 months of the pandemic were older adults with underlying medical conditions. Active surveillance of patients in hospital with COVID-19 is critical to enhancing our knowledge of the epidemiology of COVID-19 and to identifying populations at risk for severe outcomes, which will help guide Canada's response in the coming months.

The evolving epidemiology of Clostridium difficile infection in Canadian hospitals during a postepidemic period (2009-2015).

BACKGROUND: The clinical and molecular epidemiology of health care-associated Clostridium difficile infection in nonepidemic settings across Canada has evolved since the first report of the virulent North American pulsed-field gel electrophoresis type 1 (NAP1) strain more than 15 years ago. The objective of this national, multicentre study was to describe the evolving epidemiology and molecular characteristics of health care-associated C. difficile infection in Canada during a post-NAP1-epidemic period, particularly patient outcomes associated with the NAP1 strain. METHODS: Adult inpatients with C. difficile infection were prospectively identified, using a standard definition, between 2009 and 2015 through the Canadian Nosocomial Infection Surveillance Program (CNISP), a network of 64 acute care hospitals. Patient demographic characteristics, severity of infection and outcomes were reviewed. Molecular testing was performed on isolates, and strain types were analyzed against outcomes and epidemiologic trends. RESULTS: Over a 7-year period, 20 623 adult patients admitted to hospital with health care-associated C. difficile infection were reported to CNISP, and microbiological data were available for 2690 patients. From 2009 to 2015, the national rate of health care-associated C. difficile infection decreased from 5.9 to 4.3 per 10 000 patient-days. NAP1 remained the dominant strain type, but infection with this strain has significantly decreased over time, followed by an increasing trend of infection with NAP4 and NAP11 strains. The NAP1 strain was significantly associated with a higher rate of death attributable to C. difficile infection compared with non-NAP1 strains (odds ratio 1.91, 95% confidence interval [CI] 1.29-2.82). Isolates were universally susceptible to metronidazole; one was nonsusceptible to vancomycin. The proportion of NAP1 strains within individual centres predicted their rates of health care-associated C. difficile infection; for every 10% increase in the proportion of NAP1 strains, the rate of health care-associated C. difficile infection increased by 3.3% (95% CI 1.7%-4.9%). INTERPRETATION: Rates of health care-associated C. difficile infection have decreased across Canada. In nonepidemic settings, NAP4 has emerged as a common strain type, but NAP1, although decreasing, continues to be the predominant circulating strain and remains significantly associated with higher attributable mortality.

Healthcare-Associated Clostridium difficile Infections and Strain Diversity in Pediatric Hospitals in the Canadian Nosocomial Infection Surveillance Program, 2007-2011.

Children with healthcare-associated Clostridium difficile infection were identified. The incidence increased from 3.2/10,000 patient days in 2007 to 5.2/10,000 patient days in 2011 (p < 0.001). Of 169 isolates, the most common North American Pulsed-Field (NAP) types were NAP4 (n = 43; (25.4%), and NAP1 (n = 25;14.8%) while 55 (32.6%) were non-assigned NAP types.