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Contexte : Le programme de surveillance circumpolaire internationale assure la surveillance de cinq maladies bactériennes invasives : les pneumococcies invasives, les infections invasives à streptocoque du groupe A, l’Haemophilus influenzae, les infections invasives à méningocoque et les streptocoques du groupe B. Les maladies bactériennes invasives ont une charge de morbidité plus élevée dans les populations nordiques que dans le reste du Canada. Méthodologies : Afin de décrire l’épidémiologie des maladies bactériennes invasives dans le nord du Canada de 1999 à 2018, les données relatives aux pneumococcies invasives, aux infections invasives à streptocoque du groupe A, à l’Haemophilus influenzae, aux infections invasives à méningocoque et aux streptocoques du groupe B ont été extraites du programme de surveillance circumpolaire internationale et du Système canadien de surveillance des maladies à déclaration obligatoire (SSMDO) et analysées. Résultats : Les taux d’incidence annualisés des pneumococcies invasives, des infections invasives à streptocoque du groupe A, de l’Haemophilus influenzae, des streptocoques du groupe B et des infections invasives à méningocoque étaient respectivement de 23,3, 10,5, 8,9, 1,9 et 1,1 pour 100 000 habitants. L’incidence de la pneumococcie invasive, de l’infection invasive à streptocoque du groupe A et de l’Haemophilus influenzae de type b (Hib) était respectivement 2,8, 3,2 et 8,8 fois plus élevée dans le Nord du Canada que dans le reste du pays. Les taux de maladie ont diminué de manière statistiquement significative pour la pneumococcie invasive (β = -0,02) et ont augmenté de manière statistique pour l’infection invasive à streptocoque du groupe A (β = 0,08) et l’Haemophilus influenzae sérotype a (β = 0,04) pendant la période d’étude. Dans le Nord du Canada, les taux d’incidence annualisés des pneumococcies invasives, des infections invasives à streptocoque du groupe A et de l’Haemophilus influenzae étaient statistiquement plus élevés chez les résidents autochtones que chez les résidents non autochtones. Les taux d’incidence les plus élevés ont été enregistrés dans les groupes d’âge très jeunes et plus âgés. Conclusion : Les maladies bactériennes invasives représentent une charge de morbidité importante pour les populations nordiques du Canada. Les peuples autochtones, les enfants et les personnes âgées sont particulièrement exposés.

Contexte : L’Agence de la santé publique du Canada (l’Agence) a amélioré la surveillance de la rougeole depuis 1998, année où la transmission de la rougeole a été éliminée au Canada. L’objectif de ce rapport national annuel de surveillance de la rougeole est de fournir un résumé épidémiologique de l’activité de la rougeole déclarée au Canada pour 2019 afin de fournir des données probantes pour appuyer la vérification continue du statut d’élimination de la rougeole au Canada. Méthodes : Les données de surveillance de la rougeole se trouvent dans la base de données du Système canadien de surveillance de la rougeole et de la rubéole (SCSRR). Des analyses descriptives de la démographie et des facteurs de risque ont été effectuées. Les caractéristiques de l’éclosion ont été résumées et des analyses génotypiques ont été effectuées. Les données de surveillance, de laboratoire et de couverture vaccinale de 2019 ont été utilisées pour évaluer la situation du Canada par rapport aux critères essentiels de l’Organisation panaméricaine de la santé (OPS) pour la vérification de l’élimination de la rougeole. Résultats : En 2019, 113 cas de rougeole ont été signalés au Canada (taux brut d’incidence de 3,0 cas pour 1 000 000 personnes). Parmi ces cas, 42 (37 %) ont été importés au Canada, et 12 (29 %) ont entraîné une transmission supplémentaire. Les nourrissons de moins d’un an présentaient le taux d’incidence par âge le plus élevé, soit 13,1 cas pour 1 000 000 personnes. Seulement 29 % des cas contenaient une ou plusieurs doses documentées de vaccin contre la rougeole. Un cinquième (19 %) des cas ont été hospitalisé; aucun décès n’a été signalé. Des renseignements sur le génotype étaient disponibles pour 100 % des éclosions signalées en 2019 et 90 % des cas de rougeole non liés aux éclosions. Parmi les cas pour lesquels des renseignements sur le génotype étaient disponibles, 27 % étaient de type B3 et 73 % étaient de type D8. Conclusion : Même si seulement trois des quatre critères essentiels de l’OPS pour l’élimination de la rougeole ont été respectés entièrement ou partiellement, les données ne démontrent pas le rétablissement de la transmission endémique du virus de la rougeole.

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.

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.

Background: The International Circumpolar Surveillance (ICS) program conducts surveillance on five invasive bacterial diseases: pneumococcal disease (IPD), group A streptococcus (iGAS), Haemophilus influenzae (Hi), meningococcal disease (IMD) and group B streptococcus (GBS). Invasive bacterial diseases have a higher burden of disease in northern populations than the rest of Canada. Methods: To describe the epidemiology of invasive bacterial diseases in northern Canada from 1999 to 2018, data for IPD, iGAS, Hi, IMD and GBS were extracted from the ICS program and the Canadian Notifiable Diseases Surveillance System (CNDSS) and analyzed. Results: The annualized incidence rates for IPD, iGAS, Hi, GBS and IMD were 23.3, 10.5, 8.9, 1.9 and 1.1 per 100,000 population, respectively. The incidence of IPD, iGAS and Hi serotype b were 2.8, 3.2 and 8.8 times higher, respectively, in northern Canada than in the rest of Canada. Rates of disease decreased statistically significantly for IPD (β=−0.02) and increased statistically for iGAS (β=0.08) and Hi serotype a (β=0.04) during the study period. In Northern Canada, the annualized incidence rates for IPD, iGAS and Hi were statistically higher for Indigenous residents than for non-Indigenous residents. The highest incidence rates were among the very young and older age groups. Conclusion: Invasive bacterial diseases represent a high burden of disease in Canada’s northern populations. Indigenous peoples, children and seniors are particularly at risk.

ObjectivePost COVID-19 condition refers to persisting or recurring symptoms weeks after acute COVID-19 illness which can significantly impact quality of life and health systems. It is important to understand the manifestation and magnitude of this condition. The objective of this living systematic review is to summarize the prevalence of symptoms and sequelae reported by people ≥4 weeks after COVID-19 diagnosis.DesignSystematic review, meta-analysis and narrative synthesis.Data sourcesEmbase, Medline, PsychInfo, Cochrane Central and select grey literature up to April 14, 2021.MethodsWe adapted a previous search strategy used by the U.K. National Institute for Health and Care Excellence and updated it to search for new literature. Two reviewers screened references independently; one extracted data and assessed risk of bias and certainty of the evidence while another verified them. Prevalence data from laboratory-confirmed populations were meta-analyzed using a random effects model and synthesized separately in the short-term (4-12 weeks) and long-term (>12 weeks) periods after diagnosis. Data from clinically-diagnosed populations were synthesized narratively.ResultsOf the 4444 unique citations, 84 observational studies met our inclusion criteria. Over 100 post COVID-19 symptoms and sequelae were reported. Sixty-one percent (95% CI: 44-76%, low certainty) and 53% (95% CI: 41-65%, low certainty) of laboratory-confirmed individuals reported persistence or presence of one or more symptoms in the short- and long-term periods, respectively. The most prevalent symptoms in both periods included: fatigue, general pain or discomfort, shortness of breath, cognitive impairment and mental health symptoms.ConclusionsA substantial proportion of individuals reported a variety of symptoms ≥4 weeks after COVID-19 diagnosis. Due to gaps in the research base, and the low certainty of the evidence currently available, further research is needed to determine the true burden of post COVID-19 condition in the general population and in specific subgroups.PROSPERO registration numberCRD42021231476.

Respiratory specimens collected from outpatients with influenza-like illness in three Canadian provinces (British Columbia (BC), Alberta and Quebec) participating in a community-based sentinel surveillance network were prospectively screened for enterovirus-D68 (EV-D68) from 1 August to 31 December 2014 and compared to specimens collected from 1 October 2013 to 31 July 2014. Eighteen (1%) of 1,894 specimens were EV-D68-positive: 1/348 (0.3%) collected from October to December 2013 and 11/460 (2.4%) from October to December 2014, an eight-fold increase in detection rates (p=0.01), consistent with epidemic circulation in autumn 2014. The remaining EV-D68 detections were in September 2014 (6/37). Enhanced passive surveillance was also conducted on all inpatient and outpatient EV-D68 cases (n=211) detected at the BC provincial reference laboratory from 28 August to 31 December 2014. Incidence of hospitalisations was 3/100,000 overall and 21, 17, 4 and 1/100,000 among those 1 among paediatric but not adult cases. Three cases in BC with comorbidity or co-infection died and five exhibited neurological features persisting >9 months. Active surveillance in outpatient and inpatient settings is needed from more areas and additional seasons to better understand EV-D68 epidemiology and potential at-risk groups for severe or unusual manifestations.

Background Most evaluations of epidemic thresholds for influenza have been limited to internal criteria of the indicator variable. We aimed to initiate discussion on appropriate methods for evaluation and the value of cross-validation in assessing the performance of a candidate indicator for influenza activity. Methods Hospital records of in-patients with a diagnosis of confirmed influenza were extracted from the Canadian Discharge Abstract Database from 2003 to 2011 and aggregated to weekly and regional levels, yielding 7 seasons and 4 regions for evaluation (excluding the 2009 pandemic period). An alert created from the weekly time-series of influenza positive laboratory tests (FluWatch, Public Health Agency of Canada) was evaluated against influenza-confirmed hospitalizations on 5 criteria: lead/lag timing; proportion of influenza hospitalizations covered by the alert period; average length of the influenza alert period; continuity of the alert period and length of the pre-peak alert period. Results Influenza hospitalizations led laboratory positive tests an average of only 1.6 (95% CI: -1.5, 4.7) days. However, the difference in timing exceeded 1 week and was statistically significant at the significance level of 0.01 in 5 out of 28 regional seasons. An alert based primarily on 5% positivity and 15 positive tests produced an average alert period of 16.6 weeks. After allowing for a reporting delay of 2 weeks, the alert period included 80% of all influenza-confirmed hospitalizations. For 20 out of the 28 (71%) seasons, the first alert would have been signalled at least 3 weeks (in real time) prior to the week with maximum number of influenza hospitalizations. Conclusions Virological data collected from laboratories was a good indicator of influenza activity with the resulting alert covering most influenza hospitalizations and providing a reasonable pre-peak warning at the regional level. Though differences in timing were statistically significant, neither time-series consistently led the other.