COVID-19 outcome trends by vaccination status in Canada, December 2020-January 2022.

Background: The coronavirus disease 2019 (COVID-19) pandemic in Canada has evolved rapidly. Since late 2020, COVID-19 vaccines have been relied on to protect against severe outcomes in the presence of circulating variants of concern (VOC). Objective: This surveillance report provides a retrospective descriptive analysis of national trends in COVID-19 cases and severe outcomes by vaccination status, contextualizing trends against case demographics and circulating VOCs, from December 2020 to January 2022. Methods: Case and vaccination coverage surveillance data were obtained from the National COVID-19 Case Dataset and the Canadian COVID-19 Vaccination Coverage Surveillance System for 12 of 13 provinces and territories. Descriptive analyses were produced to describe trends over time among individuals aged 12 years and older by COVID-19 outcome, vaccination status, and demographics. Age-standardized and age-stratified incidence rates and incidence rate ratios were computed for cases, hospitalizations, and deaths. Results: From mid to late-2021, incidence rates for cases and severe outcomes were consistently lowest among those with a completed primary series and highest among those who were unvaccinated. Unvaccinated individuals were much more likely to be hospitalized or to die compared to those with a completed primary series in all variant periods. Age-specific rates of severe outcomes were consistently highest among those aged 80 years and older across all vaccination statuses. Conclusion: Vaccination remains one of the most important public health interventions, particularly among older adults, to protect against COVID-19 severe outcomes as the pandemic evolves. Routine monitoring of COVID-19 outcomes by vaccination status can identify changes in COVID-19 epidemiology and inform public health action and policy.

Canadian COVID-19 Outbreak Surveillance System: implementation of national surveillance during a global pandemic.

SETTING: Early in the SARS-CoV-2 pandemic, the need to develop systematic outbreak surveillance at the national level to monitor trends in SARS-CoV-2 outbreaks was identified as a priority for the Public Health Agency of Canada (PHAC). The Canadian COVID-19 Outbreak Surveillance System (CCOSS) was established to monitor the frequency and severity of SARS-CoV-2 outbreaks across various community settings. INTERVENTION: PHAC engaged with provincial/territorial partners in May 2020 to develop goals and key data elements for CCOSS. In January 2021, provincial/territorial partners began submitting cumulative outbreak line lists on a weekly basis. OUTCOMES: Eight provincial and territorial partners, representing 93% of the population, submit outbreak data on the number of cases and severity indicators (hospitalizations and deaths) for 24 outbreak settings to CCOSS. Outbreak data can be integrated with national case data to supply information on case demographics, clinical outcomes, vaccination status, and variant lineages. Data aggregated to the national level are used to conduct analyses and report on outbreak trends. Evidence from CCOSS analyses has been useful in supporting provincial/territorial outbreak investigations, informing policy recommendations, and monitoring the impact of public health measures (vaccination, closures) in specific outbreak settings. IMPLICATIONS: The development of a SARS-CoV-2 outbreak surveillance system complemented case-based surveillance and furthered the understanding of epidemiological trends. Further efforts are required to better understand SARS-CoV-2 outbreaks for Indigenous populations and other priority populations, as well as create linkages between genomic and epidemiological data. As SARS-CoV-2 outbreak surveillance enhanced case surveillance, outbreak surveillance should be a priority for emerging public health threats.

RéSUMé: CONTEXTE: Au début de la pandémie de SRAS-CoV-2, l'Agence de la santé publique du Canada (ASPC) a déterminé comme priorité la nécessité de développer un système de surveillance systématique des éclosions à l'échelle nationale afin de suivre les tendances des éclosions de SRAS-CoV-2. Le système canadien de surveillance des éclosions de COVID-19 (SCSEC) a été établi pour surveiller la fréquence et la gravité des éclosions de SRAS-CoV-2 dans différents milieux communautaires. INTERVENTION: L'ASPC s'est engagée avec les partenaires provinciaux et territoriaux en mai 2020 pour élaborer des objectifs et des éléments de données clés pour le SCSEC. En janvier 2021, les partenaires provinciaux et territoriaux ont commencé à transmettre des listes d'éclosions cumulatives hebdomadaires. RéSULTATS: Huit partenaires provinciaux et territoriaux, représentant 93 % de la population, transmettent au SCSEC des données sur les éclosions sur le nombre de cas et les indicateurs de gravité (les hospitalisations et les décès) pour 24 types de milieux. Les données sur les éclosions peuvent être intégrées avec les données nationales sur les cas pour obtenir des informations sur la démographie des cas, les résultats cliniques, le statut vaccinal et les lignées de variants. Les données agrégées à l'échelle nationale sont utilisées pour effectuer des analyses et faire rapport des tendances sur les éclosions. Les résultats des analyses du SCSEC ont été utiles pour soutenir les enquêtes provinciales/territoriales sur les éclosions, informer les recommandations politiques et surveiller l'impact des mesures de santé publique (la vaccination, les fermetures) dans des milieux d'éclosions spécifiques. IMPLICATIONS: Le développement d'un système de surveillance des éclosions de SRAS-CoV-2 a permis de complémenter la surveillance des cas et d'approfondir notre compréhension des tendances épidémiologiques. Des efforts supplémentaires sont nécessaires pour mieux comprendre les éclosions de SRAS-CoV-2 chez les populations autochtones et d'autres populations minoritaires, ainsi que pour créer des liens entre les données génomiques et les données épidémiologiques. Comme la surveillance des éclosions de SRAS-CoV-2 a enrichi la surveillance des cas, la surveillance des éclosions devrait être une priorité pour les menaces émergentes pour la santé publique.

COVID-19 outbreak trends in Canada, 2021.

Background: In January 2021, the Public Health Agency of Canada launched an outbreak surveillance system, the Canadian COVID-19 Outbreak Surveillance System (CCOSS), with the goal of monitoring incidence and severity of coronavirus disease 2019 (COVID-19) outbreaks across various community settings and complementing case surveillance. Methods: Seven provinces were included in this report; these provinces submitted weekly cumulative COVID-19 outbreak line lists to CCOSS in 2021. Data includes administrative variables (e.g. date outbreak declared, date outbreak declared over, outbreak identifier), 24 outbreak settings, and number of confirmed cases and outcomes (hospitalization, death). Descriptive analyses for COVID-19 outbreaks across Canada from January 3, 2021, to January 1, 2022, were performed examining trends over time, severity, and outbreak size. Results: Incidence of outbreaks followed similar trends to case incidence. Outbreaks were most common in school and childcare settings (39%) and industrial/agricultural settings (21%). Outbreak size ranged from 2 to 639 cases per outbreak; the median size was four cases per outbreak. Correctional facilities had the largest median outbreak size with 18 cases per outbreak, followed by long-term care facilities with 10 cases per outbreak. During periods of high case incidence, outbreaks may be under-ascertained due to limited public health capacity, or reporting may be biased towards high-risk settings prioritized for testing. Outbreaks reported to CCOSS were dominated by jurisdictions with the largest populations. Conclusion: The trends illustrate that COVID-19 outbreaks in 2021 were reported most frequently in community settings such as schools; however, the largest outbreaks occurred in congregate living settings. The information gathered from outbreak surveillance complemented case incidence trends and furthered understanding of COVID-19 in Canada.

Measles surveillance in Canada, 2019.

BACKGROUND: The Public Health Agency of Canada (PHAC) has conducted enhanced measles surveillance since 1998, the year endemic measles transmission was eliminated in Canada. The objective of this annual national measles surveillance report is to provide an epidemiologic summary of measles activity reported in Canada for 2019 in order to provide evidence to support the continued verification of Canada's measles elimination status. METHODS: Measles surveillance data are housed in the Canadian Measles and Rubella Surveillance System (CMRSS) database. Descriptive analyses of demographics and risk factors were performed. Outbreak characteristics were summarized and genotypic analyses conducted. Surveillance, laboratory and vaccine coverage data for 2019 were used to assess Canada's status against the Pan American Health Organization (PAHO) essential criteria for the verification of measles elimination. RESULTS: In 2019, 113 measles cases were reported in Canada (crude incidence rate of 3.0 cases per 1,000,000 population). Of these cases, 42 (37%) were imported into Canada, and of the imported cases, 12 (29%) resulted in further transmission. Infants younger than one year had the highest age-specific incidence rate at 13.1 cases per 1,000,000 population. Only 29% of cases had one or more documented doses of measles-containing vaccine. One-fifth (19%) of cases were hospitalized; no deaths were reported. Genotype information was available for 100% of outbreaks reported in 2019 and 90% of non-outbreak-related measles cases; of cases with genotype information available, 27% were B3 and 73% were D8. CONCLUSION: Despite meeting/partially meeting only three out of four of PAHO's essential criteria for measles elimination status, there is no evidence that endemic measles transmission has been reestablished in Canada.

Measles surveillance in Canada: 2018.

BACKGROUND: Measles has been eliminated in Canada since 1998. Every year, the Public Health Agency of Canada presents epidemiologic evidence to the Pan American Health Organization (PAHO) to verify that measles continues to be eliminated in Canada. The objectives of this article are to: provide an epidemiologic summary of measles activity reported in 2018 in Canada, and provide documented evidence to support the continued verification of measles elimination status in Canada. METHODS: Measles surveillance data were captured by the Canadian Measles and Rubella Surveillance System (CMRSS) and descriptive analyses of demographics and risk factors were performed. Outbreak characteristics were summarized and genotypic analyses conducted. Surveillance data for 2018 were evaluated against PAHO's essential criteria for measles elimination status. RESULTS: In 2018, 29 measles cases were reported across five provinces in Canada, an incidence rate of 0.8 cases per 1,000,000 population. Of these 29 cases, 16 were imported and five resulted in further transmission within Canada. The age-specific incidence rate was highest among those aged younger than one year (10.2 cases per 1,000,000 population, n=4). Only nine cases were considered up-to-date for measles vaccination, and 11 cases were hospitalized. Genotype information was available for most of the measles cases (n=27); they were all found to be genotypes that circulated globally in 2018. Canada met or partially met three out of four of PAHO's criteria for verification of measles elimination. CONCLUSION: Although importations and areas of low vaccination coverage continue to challenge Canada's elimination status, there is no evidence that endemic transmission of the measles virus has been re-established. Canada maintains its measles elimination status.

Longitudinal Multicenter Analysis of Outcomes After Cessation of Control Measures for Vancomycin-Resistant Enterococci.

OBJECTIVE To assess clinically relevant outcomes after complete cessation of control measures for vancomycin-resistant enterococci (VRE). DESIGN Quasi-experimental ecological study over 3.5 years. METHODS All VRE screening and isolation practices at 4 large academic hospitals in Ontario, Canada, were stopped on July 1, 2012. In total, 618 anonymized abstracted charts of patients with VRE-positive clinical isolates identified between July 1, 2010, and December 31, 2013, were reviewed to determine whether the case was a true VRE infection, a VRE colonization or contaminant, or a true VRE bacteremia. All deaths within 30 days of the last VRE infection were also reviewed to determine whether the death was fully or partially attributable to VRE. All-cause mortality was evaluated over the study period. Generalized estimating equation methods were used to cluster outcome rates within hospitals, and negative binomial models were created for each outcome. RESULTS The incidence rate ratio (IRR) for VRE infections was 0.59 and the associated P value was .34. For VRE bacteremias, the IRR was 0.54 and P=.38; for all-cause mortality the IRR was 0.70 and P=.66; and for VRE attributable death, the IRR was 0.35 and P=.49. VRE control measures were not significantly associated with any of the outcomes. Rates of all outcomes appeared to increase during the 18-month period after cessation of VRE control measures, but none reached statistical significance. CONCLUSION Clinically significant VRE outcomes remain rare. Cessation of all control measures for VRE had no significant attributable adverse clinical impact. Infect Control Hosp Epidemiol 2016;1-7.