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 18 months (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 16 months 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.

IMPORTANCEGiven limited COVID-19 vaccine availability early in the pandemic, optimizing immunization strategies was of paramount importance. Ring vaccination has been used successfully to control transmission of other airborne respiratory viruses. OBJECTIVE To assess the association of a ring vaccination intervention on COVID-19 spread in the initial epicenter of SARS-CoV-2 Alpha variant transmission in Montreal, Canada. DESIGN, SETTING, AND PARTICIPANTS This cohort study compared COVID-19 daily disease risk in 3 population-based groups of neighborhoods in Montreal, Canada, defined by their interventionspecific vaccine coverage at the neighborhood level: the primary intervention group (500 or more vaccinated persons per 10 000 persons), secondary intervention group (95 to 499), and control group (0 to 50). The groups were compared within each of 3 time periods: before intervention

Objective: 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. A systematic review was conducted to assess the current evidence regarding the validity of sexually transmitted and blood-borne infection (STBBI) testing using DBS specimens. Methods: A literature search was conducted using a peer-reviewed search strategy. Eligibility criteria included studies reporting use of DBS specimens for STBBI testing in populations 15 years of age or older. The intervention of interest was either commercially available or in-house tests used to detect STBBI from DBS specimens. Studies that reported 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. Results: A total of 6,706 records were identified. Of these records, 169 full-text articles met the criteria for inclusion. The STBBI with the most articles reporting a measure of validity for testing on DBS was HIV (n=73), followed by HCV (n=63), HBV (n=33), syphilis (n=7), HAV (n=5), HSV (n=5), HTLV (n=3), and HPV (n=1). The majority of studies reported high sensitivity (>=90%) and specificity (>=90%). However, the quality of the studies varied greatly. No evidence was found on the validity of chlamydia and gonorrhoea testing using DBS specimens. Conclusion: Our findings support the validity of DBS testing for STBBI surveillance where sufficient evidence was available, but validity is highly dependent on thorough method development and validation. Keywords: dried blood spot testing, sexually transmitted diseases, blood-borne infections, biosurveillance