Testing for human immunodeficiency virus (HIV) and hepatitis C virus (HCV) using dried blood spot (DBS) specimens has been an integral part of bio-behavioural surveillance in Canada for almost two decades, though less is known regarding the use of DBS in surveillance of other sexually transmitted and blood-borne infections (STBBI). A systematic review was conducted using a peer-reviewed search strategy to assess the current evidence regarding the validity of STBBI testing using DBS specimens. Eligibility criteria included studies reporting use of DBS specimens for STBBI testing with either commercially available or “in-house” tests in populations 15 years of age or older. Studies reporting a measure of validity such as sensitivity, specificity, positive and negative predictive values were eligible for inclusion. Quality of studies and risk of bias were assessed using the QUADAS-2 tool. A total of 7,132 records were identified. Of these, 174 met the criteria for inclusion. Among the studies that reported validity measures, a substantial proportion demonstrated high sensitivity (≥90%) in 62.5% of cases (N= 334/534 sensitivity measurements), and high specificity (≥90%) was observed in 84.9% of instances (N= 383/451 specificity measurements). However, the quality of the studies varied greatly. Our findings support the validity of the use of DBS specimens in STBBI testing where sufficient evidence was available, but validity is highly dependent on thorough method development and validation.

Background: Estimates of the number of hepatitis C virus (HCV) infections are important for monitoring efforts aimed at preventing disease transmission, especially following the introduction of a highly effective treatment.This report provides updated estimates of HCV incidence, prevalence, undiagnosed proportion and treatment in Canada.Methods: A combination of back calculation modelling and a modified version of the workbook method were used to estimate the incidence and prevalence of anti-HCV positive persons, the prevalence of chronic HCV infection and the undiagnosed proportion.The number of people treated for chronic HCV was estimated using administrative pharmaceutical data.Results: An estimated 9,470 new infections occurred in 2019, corresponding to an incidence rate of 25 per 100,000 population, a 7.7% decrease since 2015.The estimated prevalence of anti-HCV antibodies in the Canadian population was 1.03% (plausible range: 0.83%-1.38%),and the estimated prevalence of chronic HCV was 0.54% (plausible range: 0.40%-0.79%).The overall proportion of anti-HCV positive persons who were undiagnosed was estimated at 24% of all infections, with individuals born between 1945 and 1975 being the priority population the most likely to be undiagnosed.An estimated 74,500 people with chronic HCV have been treated since the introduction of direct-acting antivirals in 2014. Conclusion:Estimates of HCV incidence and prevalence are key metrics to guide interventions and resource allocation.While our estimates show that HCV incidence has decreased in Canada in recent years and treatment of chronic HCV has continued to increase, ongoing efforts are required to reduce the burden of HCV in Canada.

Contexte : Les estimations du nombre d'infections par le virus de l'hépatite C (VHC) sont importantes pour le suivi des efforts visant à prévenir la transmission de la maladie, en particulier suite à l'introduction d'un traitement hautement efficace.Ce rapport fournit des estimations actualisées de l'incidence, de la prévalence, de la proportion non diagnostiquée et du traitement du VHC au Canada.Méthodes : Une combinaison de modélisation par rétrocalcul et une version modifiée de la méthode du classeur ont été utilisées pour estimer l'incidence et la prévalence des personnes séropositives pour le VHC, la prévalence de l'infection chronique par le VHC et la proportion non diagnostiquée.Le nombre de personnes traitées pour le VHC chronique a été estimé à partir de données administratives pharmaceutiques.Résultats : On estime à 9 470 le nombre de nouvelles infections survenues en 2019, ce qui correspond à un taux d'incidence de 25 pour 100 000 habitants, soit une baisse de 7,7 % depuis 2015.La prévalence estimée des anticorps anti-VHC dans la population canadienne était de 1,03 % (intervalle plausible : 0,83 %-1,38 %), et la prévalence estimée du VHC chronique était de 0,54 % (intervalle plausible : 0,40 %-0,79 %).La proportion globale de personnes anti-VHC positives qui n'ont pas été diagnostiquées a été estimée à 24 % de toutes les infections, les personnes nées entre 1945 et 1975 étant la population prioritaire la plus susceptible de ne pas être diagnostiquée.On estime que 74 500 personnes atteintes du VHC chronique ont été traitées depuis l'introduction des antiviraux à action directe en 2014. Conclusion :Les estimations de l'incidence et de la prévalence du VHC sont des paramètres clés pour guider les interventions et l'allocation des ressources.Bien que nos estimations montrent que l'incidence du VHC a diminué au Canada au cours des dernières années et que le traitement du VHC chronique a continué d'augmenter, des efforts continus sont nécessaires pour réduire le fardeau du VHC au Canada.

Delaying vaccination increases the period of vulnerability of children against vaccine-preventable diseases. We used a nationally representative sample of Canadian two-year-old children to explore factors associated with delays in the uptake of the first dose of measles-containing vaccine, recommended in Canada for children at 12 months of age. Distribution of delays was determined using data from the 2013 Childhood National Immunization Coverage Survey. Logistic regression was used to examine sociodemographic factors and knowledge, attitudes and beliefs (KAB) associated with the two outcomes of interest: delays of one to six months (vaccination at 13 to 18 months of age) and delays of seven to 18months (vaccination at 19 to 23 months of age). Overall, 69% (95% confidence interval [CI] 67-71) of children received their first valid dose on time. Twenty-nine percent (95% CI 27-31) and 11% (95% CI 9-12) of children were unvaccinated before turning 13 and 16months of age, respectively. Factors associated with delays of one to six months were being a girl, being born outside Canada, and the jurisdiction of residence. Being from a single-parent family, being born outside Canada and the jurisdiction of residence were associated with delays of seven to 18 months, suggesting that potential barriers might be at play. Associations between KAB and vaccination delays indicate that vaccine hesitancy could contribute to measles vaccination delays in Canada. Barriers in accessing vaccination services and the role of vaccine hesitancy in timely vaccination must be better understood to reduce vaccination delays in toddlers in Canada.