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Many vaccines require higher/additional doses or adjuvants to provide adequate protection for people with HIV (PWH). Our objective was to compare COVID-19 vaccine immunogenicity in PWH to HIV-negative individuals.In a Canadian multi-center prospective, observational cohort of PWH receiving at least two COVID-19 vaccinations, we measured vaccine-induced immunity at 3 and 6 months post 2nd and 1-month post 3rd doses.The primary outcome was the percentage of PWH mounting vaccine-induced immunity [co-positivity for anti-IgG against SARS-CoV2 Spike(S) and receptor-binding domain proteins] 6 months post 2nd dose. Univariable and multivariable logistic regressions were used to compare COVID-19-specific immune responses between groups and within subgroups.Data from 294 PWH and 267 controls were analyzed. Immunogenicity was achieved in over 90% at each time point in both groups. The proportions of participants achieving comparable anti-receptor-binding domain levels were similar between the group at each time point. Anti-S IgG levels were similar by group at month 3 post 2nd dose and 1-month post 3rd dose. A lower proportion of PWH vs. controls maintained vaccine-induced anti-S IgG immunity 6 months post 2nd dose [92% vs. 99%; odds ratio: 0.14 (95% confidence interval: 0.03, 0.80; P = 0.027)]. In multivariable analyses, neither age, immune non-response, multimorbidity, sex, vaccine type, or timing between doses were associated with reduced IgG response.Vaccine-induced IgG was elicited in the vast majority of PWH and was overall similar between groups. A slightly lower proportion of PWH vs. controls maintained vaccine-induced anti-S IgG immunity 6 months post 2nd dose demonstrating the importance of timely boosting in this population.

Understanding the roots of Covid-19 vaccine hesitancy in at-risk groups, such as persons living with HIV (PLWH), is of utmost importance. We developed a modified Vaccine Hesitancy Scale (VHS) questionnaire using items from the National Advisory Committee on Immunization Acceptability Matrix. To examine factors associated with receiving COVID-19 vaccine and the link between vaccine attitudes and beliefs with vaccine behavior, PLWH were recruited via social media and community-based organizations (February-May 2022). Descriptive statistics were used to summarize results. Total VHS score was generated by adding Likert scale scores and linear regression models used to compare results between participants who received or did not receive COVID-19 vaccines. Logistic regression models were used to identify factors associated with vaccine uptake. A total of 246 PLWH indicated whether they received a COVID-19 vaccine. 89% received ≥ 1 dose. Mean total VHS(SD) for persons having received ≥ 1 COVID-19 vaccine was 17.8(6.2) vs. 35.4(9.4) for participants not having received any COVID-19 vaccine. Persons who received ≥ 1 dose were significantly older than those who had not received any (48.4 ± 13.8 vs. 34.0 ± 7.7 years, p ≥ 1dose were increased 2.4-fold [95% CI 1.6, 3.5] with each increase in age of 10 years (p

Background Real-world evidence of human papillomavirus (HPV) vaccine effectiveness (VE) against longitudinal outcomes is lacking among gay, bisexual, and other men who have sex with men (GBM). We compared 12-month incidence and persistence of anal HPV infection between vaccinated and unvaccinated GBM. Methods We recruited GBM aged 16–30 years in Montreal, Toronto, and Vancouver, Canada, from 2017 to 2019. Participants were followed over a median of 12 months (interquartile range, 12–13 months). Participants self-reported HPV vaccination and self-collected anal specimens for HPV DNA testing. We calculated prevalence ratios (PR) for 12-month cumulative incidence and persistence with ≥1 quadrivalent vaccine type (HPV 6/11/16/18) between vaccinated (≥1 dose at baseline) and unvaccinated participants using a propensity score-weighted, modified Poisson regression. Results Among 248 participants, 109 (44.0%) were vaccinated at baseline, of whom 62.6% received 3 doses. PRs for HPV 6/11/16/18 were 0.56 (95% confidence interval [CI], .24–1.31) for cumulative incidence and 0.53 (95% CI, .25–1.14) for persistence. PRs were 0.23 (95% CI, .05–1.03) and 0.08 (95% CI, .01–.59) for incidence and persistence, respectively, among participants who received their first dose at age ≤23 years and 0.15 (95% CI, .03–.68) and 0.12 (95% CI, .03–.54) among participants who were sexually active for ≤5 years before vaccination. Conclusions Findings support national recommendations for HPV vaccination at younger ages or soon after sexual debut.

People with HIV were underrepresented in coronavirus disease 2019 (COVID-19) vaccine clinical trials. We estimated vaccine effectiveness (VE) against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection for the BNT162b2, mRNA-1273, and ChAdOx1 vaccines among a population-based cohort of people with HIV in Ontario, Canada.Test-negative design.We identified people with HIV aged ≥19 years who were tested for SARS-CoV-2 by RT-PCR between December 14, 2020 (first availability of COVID-19 vaccines) and November 21, 2021 (pre-Omicron circulation). Outcomes included any infection, symptomatic infection, and COVID-19-related hospitalization/death. We compared the odds of vaccination between test-positive cases and test-negative controls using multivariable logistic regression with adjustment for age, sex, region, calendar time, SARS-CoV-2 test histories, influenza vaccination, comorbidities, and neighborhood-level socio-economic status. VE was derived as (1 - adjusted odds ratio) × 100%.Among 21 023 adults living with HIV, there were 801 (8.3%) test-positive cases and 8,879 (91.7%) test-negative controls. 20.1% cases and 47.8% of controls received ≥1 COVID-19 vaccine dose; among two-dose recipients, 93.4% received ≥1 mRNA dose. Two-dose VE ≥7 days before specimen collection was 82% (95% confidence interval [CI] = 74-87%) against any infection, 94% (95% CI = 82-98%) against symptomatic infection, and 97% (95% CI = 85-100%) against hospitalization/death. Against any infection, VE declined from 86% (95% CI = 77-92%) within 7-59 days after the second dose to 66% (95% CI = -15-90%) after ≥180 days; we did not observe evidence of waning protection for other outcomes.Two doses of COVID-19 vaccine offered substantial protection against symptomatic illness and hospitalization/death in people with HIV prior to the emergence of the Omicron variant. Our findings do not support a broad conclusion that COVID-19 VE is lower among people with HIV in populations that, for the most part, are attending HIV care, taking antiretroviral medication, and are virally suppressed.

Using observational data, human papillomavirus vaccination was associated with a lower anal prevalence of vaccine-preventable types among young, sexually active gay and bisexual men soon after implementation of publicly funded vaccination programs. Supplemental digital content is available in the text., Background Starting in 2015, human papillomavirus (HPV) vaccine has been publicly funded for gay, bisexual, and other men who have sex with men (GBM) 26 years or younger in Canada. Methods Self-identified GBM who reported having sex with another man within the past 6 months were enrolled using respondent-driven sampling (RDS) between February 2017 and August 2019 in Montreal, Toronto, and Vancouver, Canada. Men aged 16 to 30 years self-collected anal specimens for HPV-DNA testing. Prevalence was estimated using RDS-II weights. We compared the prevalence of quadrivalent (HPV-6/11/16/18) and 9-valent (HPV-6/11/16/18/31/33/45/52/58) vaccine types between GBM who self-reported HPV vaccination (≥1 dose) and those reporting no vaccination using a modified Poisson regression for binary outcomes. Results Among 645 GBM who provided a valid anal specimen (median age, 26 years; 5.9% HIV positive), 40.3% reported receiving ≥1 dose of HPV vaccine, of whom 61.8% received 3 doses. One-quarter were infected with ≥1 quadrivalent type (crude, 25.7%; RDS weighted, 24.4%). After adjustment for potential confounders, vaccinated GBM had a 27% lower anal prevalence of quadrivalent types compared with unvaccinated GBM (adjusted prevalence ratio [aPR], 0.73; 95% confidence interval [CI], 0.54–1.00). Lower prevalence ratios were found among vaccinated participants who were vaccinated >2 years before enrollment (aPR, 0.47; 95% CI, 0.25–0.86) or received their first vaccine dose at age ≤23 years (aPR, 0.64; 95% CI, 0.42–0.99). Point estimates were similar for ≥2 or 3 doses and 9-valent types. Conclusions Human papillomavirus vaccination was associated with a lower anal prevalence of vaccine-preventable HPV types among young, sexually active GBM. Findings will help inform shared decision making around HPV vaccination for GBM and their healthcare providers.

We estimated the effectiveness of COVID-19 vaccines against laboratory-confirmed SARS-CoV-2 infection among people living with HIV (PLWH) and compared estimates with a matched HIV-negative cohort.We used the British Columbia COVID-19 Cohort, a population-based data platform which integrates COVID-19 data on SARS-CoV-2 tests, laboratory-confirmed cases, and immunizations with provincial health services data. Vaccine effectiveness (VE) was estimated with a test-negative design using multivariable logistic regression.Adjusted VE against SARS-CoV-2 infection was 79.2% (52.5, 90.9%) 7-59 days after two doses, rising to 91.6% (75.2, 97.2%) between 60-89 days. VE was preserved four to six months following receipt of 2 doses after which slight waning was observed (72.7% [39.1, 87.8%]). In the matched cohort (n=375 043), VE peaked at 91.0% (90.5, 91.5%) 7-59 days after 2 doses and was sustained for up to four months after which evidence of waning was observed, dropping to 83.8% (82.9, 84.7%) between four to six months.Receipt of two COVID-19 vaccines doses was effective against SARS-CoV-2 infection among PLWH pre-Omicron. VE estimates appeared to peak later in PLWH compared to the matched HIV-negative cohort and the degree of waning was relatively quicker in PLWH; however, overall estimates were comparable in both populations.

Although clinical trials are necessary for vaccine approval, observational epidemiology will be required to evaluate the long-term effectiveness, safety, and population impacts of newly approved COVID-19 vaccines under real-world field conditions. In this commentary, I argue that a hybrid approach that combines new data sources and tools, including COVID-19 vaccine registries, with traditional epidemiological methods will be needed to evaluate COVID-19 vaccines using observational epidemiology. Wherever possible, primary data collection, active surveillance, and linkage with existing population-based cohorts should be leveraged to supplement secondary data sources and passive surveillance systems. Evidence-informed public health decision making around provincial COVID-19 immunization programs will need to account for potential biases, incomplete or conflicting information, and heterogeneity across subpopulations.RéSUMé: Des essais cliniques sont nécessaires à l’approbation des vaccins, mais il faudra recourir à l’épidémiologie d’observation pour évaluer en conditions réelles de terrain l’efficacité à long terme, l’innocuité et les effets sur les populations des vaccins contre la COVID-19 nouvellement approuvés. Dans ce commentaire, je fais valoir qu’il faudra adopter une démarche hybride combinant de nouvelles sources de données et de nouveaux outils, dont les registres de vaccins anti-COVID-19, et des méthodes épidémiologiques classiques pour évaluer les vaccins anti-COVID-19 à l’aide de l’épidémiologie d’observation. Dans la mesure du possible, il faudra utiliser la collecte de données primaires, la surveillance active et les maillages avec les cohortes populationnelles existantes pour compléter les sources de données secondaires et les systèmes de surveillance passive. Les décisions de santé publique éclairées par les données probantes sur les programmes d’immunisation provinciaux contre la COVID-19 devront tenir compte des biais possibles, des informations incomplètes ou contradictoires et de l’hétérogénéité des sous-populations.

Starting in 2015/16, most Canadian provinces introduced publicly-funded human papillomavirus (HPV) vaccination programs for gay, bisexual, and other men who have sex with men (GBM) aged ≤ 26 years. We estimated 12-month changes in HPV vaccine coverage among community-recruited GBM from 2017 to 2021 and identified baseline factors associated with vaccine initiation (≥1 dose) or series completion (3 doses) among participants who were unvaccinated or partially vaccinated at baseline.We recruited sexually-active GBM aged ≥ 16 years in Montreal, Toronto, and Vancouver, Canada, from 02/2017 to 08/2019 and followed them over a median of 12 months (interquartile range = 12-13 months). We calculated the proportion who initiated vaccination (≥1 dose) or completed the series (3 doses) by 12-month follow-up. Analyses were stratified by city and age-eligibility for the publicly-funded programs at baseline (≤26 years or 26 years). We used multivariable logistic regression to identify baseline factors associated with self-reported incident vaccine initiation or series completion.Among 165 unvaccinated participants aged ≤ 26 years at baseline, incident vaccine initiation (≥1 dose) during follow-up was 24.1% in Montreal, 33.3% in Toronto, and 38.9% in Vancouver. Among 1,059 unvaccinated participants aged 26 years, incident vaccine initiation was 3.4%, 8.9%, and 10.9%, respectively. Higher education and trying to access pre-exposure prophylaxis for HIV were associated with incident vaccination among those aged ≤ 26 years, while younger age, residing in Vancouver (vs. Montreal), being diagnosed with anogenital warts, having both government and private extended medical insurance, and being vaccinated against influenza were associated with incident vaccination among those aged 26 years.We observed substantial gains in HPV vaccine coverage among young GBM within 5 + years of targeted program implementation, but gaps remain, particularly among older men who are ineligible for publicly-funded programs. Findings suggest the need for expanded public funding or insurance coverage for HPV vaccines.

Influenza viruses continually evolve to evade population immunity, and the different lineages are assigned into clades based on shared mutations. We have developed a publicly available computational workflow, the Influenza Classification Suite, for rapid clade mapping of sequenced influenza viruses. This suite provides a user‐friendly workflow implemented in Galaxy to automate clade calling and antigenic site extraction. Workflow input includes clade definition and amino acid index array files, which can be customized to identify any clades of interest. The Influenza Classification Suite provides rapid, high‐resolution understanding of circulating influenza strain evolution to inform influenza vaccine effectiveness and the need for potential vaccine reformulation.

Women living with HIV are at higher risk for human papillomavirus (HPV)-related dysplasia and cancers and thus are prioritized for HPV vaccination. We measured HPV vaccine uptake among women engaged in HIV care in Ontario, Canada, and identified socio-demographic, behavioural, and clinical characteristics associated with HPV vaccination. During annual interviews from 2017 to 2020, women participating in a multi-site, clinical HIV cohort responded to a cross-sectional survey on HPV vaccine knowledge and receipt. We used logistic regression to derive age-adjusted odds ratios and 95% confidence intervals (CI) for factors associated with self-reported vaccine initiation (≥1 dose) or series completion (3 doses). Among 591 women (median age = 48 years; interquartile range = 40-56 years), 13.2% (95%CI = 10.5-15.9%) had received ≥1 dose. Of those vaccinated, 64.6% had received 3 doses. Vaccine initiation (≥1 dose) was significantly higher among women aged 20-29 years at 31.0% but fell to 13.9% in those aged 30-49 years and 10% in those aged ≥50 years. After age adjustment, vaccine initiation was significantly associated with being employed (vs. unemployed but seeking work), income $40,000-$59,999 (vs.$20,000), being married/common-law (vs. single), living with children, immigrating to Canada5 years ago (vs. immigrating ≤5 years ago), never smoking (vs. currently smoking), and being in HIV care longer (per 10 years). Similar factors were identified for series completion (3 doses). HPV vaccine uptake remains low among women living with HIV in our cohort despite regular engagement in care. Recommendations for improving uptake include education of healthcare providers, targeted community outreach, and public funding of HPV vaccination.

Vaccine effectiveness (VE) against influenza B was derived separately for Victoria and Yamagata lineages across 8 seasons (2010–2011 to 2017–2018) in Canada when trivalent influenza vaccine was predominantly used. VE was ≥50% regardless of lineage match to circulating viruses, except when the vaccine strain was unchanged from the prior season.

Influenza vaccine effectiveness against influenza and noninfluenza respiratory viruses (NIRVs) was assessed by test-negative design using historic datasets of the community-based Canadian Sentinel Practitioner Surveillance Network, spanning 2010–2011 to 2016–2017. Vaccine significantly reduced the risk of influenza illness by >40% with no effect on coronaviruses or other NIRV risk.

Background The influenza A(H3N2) vaccine was updated from clade 3C.3a in 2015–2016 to 3C.2a for 2016–2017 and 2017–2018. Circulating 3C.2a viruses showed considerable hemagglutinin glycoprotein diversification and the egg-adapted vaccine also bore mutations. Methods Vaccine effectiveness (VE) in 2016–2017 and 2017–2018 was assessed by test-negative design, explored by A(H3N2) phylogenetic subcluster and prior season’s vaccination history. Results In 2016–2017, A(H3N2) VE was 36% (95% confidence interval [CI], 18%–50%), comparable with (43%; 95% CI, 24%–58%) or without (33%; 95% CI, −21% to 62%) prior season’s vaccination. In 2017–2018, VE was 14% (95% CI, −8% to 31%), lower with (9%; 95% CI, −18% to 30%) versus without (45%; 95% CI, −7% to 71%) prior season’s vaccination. In 2016–2017, VE against predominant clade 3C.2a1 viruses was 33% (95% CI, 11%–50%): 18% (95% CI, −40% to 52%) for 3C.2a1a defined by a pivotal T135K loss of glycosylation; 60% (95% CI, 19%–81%) for 3C.2a1b (without T135K); and 31% (95% CI, 2%–51%) for other 3C.2a1 variants (with/without T135K). VE against 3C.2a2 viruses was 45% (95% CI, 2%–70%) in 2016–2017 but 15% (95% CI, −7% to 33%) in 2017–2018 when 3C.2a2 predominated. VE against 3C.2a1b in 2017–2018 was 37% (95% CI, −57% to 75%), lower at 12% (95% CI, −129% to 67%) for a new 3C.2a1b subcluster (n = 28) also bearing T135K. Conclusions Exploring VE by phylogenetic subcluster and prior vaccination history reveals informative heterogeneity. Pivotal mutations affecting glycosylation sites, and repeat vaccination using unchanged antigen, may reduce VE.

Summary Age-related differences in influenza B lineage infection were assessed by the community-based Canadian Sentinel Practitioner Surveillance Network between 2010–2011 and 2015–2016. Influenza B(Victoria) cases were on average 20 years younger than B(Yamagata) cases, with the latter showing a bimodal age distribution., Age-related differences in influenza B lineage detection were explored in the community-based Canadian Sentinel Practitioner Surveillance Network (SPSN) from 2010–2011 to 2015–2016. Whereas >80% of B(Victoria) cases were

Background The antigenic distance hypothesis (ADH) predicts that negative interference from prior season's influenza vaccine (v1) on the current season's vaccine (v2) protection may occur when the antigenic distance is small between v1 and v2 (v1 ≈ v2) but large between v1 and the current epidemic (e) strain (v1 ≠ e). Methods Vaccine effectiveness (VE) against medically attended, laboratory-confirmed influenza A(H3N2) illness was estimated by test-negative design during 3 A(H3N2) epidemics (2010-2011, 2012-2013, 2014-2015) in Canada. Vaccine effectiveness was derived with covariate adjustment across v2 and/or v1 categories relative to no vaccine receipt among outpatients aged ≥9 years. Prior vaccination effects were interpreted within the ADH framework. Results Prior vaccination effects varied significantly by season, consistent with the ADH. There was no interference by v1 in 2010-2011 when v1 ≠ v2 and v1 ≠ e, with comparable VE for v2 alone or v2 + v1: 34% (95% confidence interval [CI] = -51% to 71%) versus 34% (95% CI = -5% to 58%). Negative interference by v1 was suggested in 2012-2013 with nonsignificant reduction in VE when v1 ≈ v2 and v1 ≠ e: 49% (95% CI = -47% to 83%) versus 28% (95% CI = -12% to 54%). Negative effects of prior vaccination were pronounced and statistically significant in 2014-2015 when v1 ≡ v2 and v1 ≠ e: 65% (95% CI = 25% to 83%) versus -33% (95% CI = -78% to 1%). Conclusions Effects of repeat influenza vaccination were consistent with the ADH and may have contributed to findings of low VE across recent A(H3N2) epidemics since 2010 in Canada.

This study examined factors associated with health care use in an ethnically diverse Canadian sample of homeless adults with mental illness, a particularly disadvantaged group.Baseline survey data were available from five sites across Canada for 2,195 At Home/Chez Soi demonstration project participants. Negative binomial regression models examined the relationship between racial-ethnic or cultural group membership (white, N=1,085; Aboriginal, N=476; black, N=244; and other ethnoracial minority groups, N=390) and self-reported emergency department (ED) visits and hospitalizations in the past six months and past-month visits to a medical, other clinical, or social service provider. Adjusted models included other predisposing, enabling, and need factors, based on Andersen's behavioral model for vulnerable populations.Compared with white participants, black participants had a lower rate of ED visits (adjusted rate ratio [ARR]=.54, 95% confidence interval [CI]=.43-.69) and Aboriginal participants had a lower rate of medical visits (ARR=.84, CI=.71-.99) and a higher rate of visits to social service providers (ARR=1.54, CI=1.18-2.01). Participants in other ethnoracial minority groups had a higher rate of social service provider visits than white participants (ARR=1.44, CI=1.10-1.89). Access to a family physician, having at least high school education, and high needs for mental health services were associated with greater use of ED and medical visits and hospitalizations. Rates of ED and medical visits were lower with increased age and better physical health.In a system of universal health insurance that prioritizes access to and quality of care, the presence of racial-ethnic disparities experienced by this vulnerable population merits further attention.

In January 2015, British Columbia, Canada, reported avian influenza A(H7N9) virus infection in 2 travelers returning from China who sought outpatient care for typical influenza-like illness. There was no further spread, but serosurvey findings showed broad population susceptibility to H7N9 virus. Travel history and timely notification are critical to emerging pathogen detection and response.

We investigated sex as a potential modifier of influenza vaccine effectiveness (VE) between 2010–2011 and 2016–2017 in Canada. Overall VE was 49% (95% confidence interval [CI], 43% to 55%) for females and 38% (95% CI, 28% to 46%) for males (absolute difference [AD], 11%; P = .03). Sex differences were greatest for influenza A(H3N2) (AD, 17%; P = .07) and B(Victoria) (AD, 20%; P = .08) compared with A(H1N1)pdm09 (AD, 10%; P = .19) or B(Yamagata) (AD, –3%; P = .68). They were also more pronounced in older adults ≥50 years (AD, 19%; P = .03) compared with those

Using a test-negative design, we assessed interim vaccine effectiveness (VE) for the 2017/18 epidemic of co-circulating influenza A(H3N2) and B(Yamagata) viruses. Adjusted VE for influenza A(H3N2), driven by a predominant subgroup of clade 3C.2a viruses with T131K + R142K + R261Q substitutions, was low at 17% (95% confidence interval (CI): −14 to 40). Adjusted VE for influenza B was higher at 55% (95% CI: 38 to 68) despite prominent use of trivalent vaccine containing lineage-mismatched influenza B(Victoria) antigen, suggesting cross-lineage protection.

BACKGROUND Canada's Sentinel Physician Surveillance Network links genetic, antigenic, and vaccine effectiveness (VE) measures in an integrated platform of influenza monitoring, described here for the 2013-2014 influenza season of resurgent A(H1N1)pdm09 and late-season type B activity. METHODS VE was estimated as [1 - odds ratio] × 100% and compared vaccination status between individuals who tested positive (cases) and those who tested negative (controls) for influenza virus. Vaccine-virus relatedness was assessed by genomic sequence analysis and hemagglutination inhibition assays. RESULTS Analyses included 1037 controls (of whom 33% were vaccinated) and 663 cases (of whom 14% were vaccinated). A total of 415 cases tested positive for A(H1N1)pdm09 virus, 15 tested positive for A(H3N2) virus, 191 tested positive for B/Yamagata-lineage virus, 6 tested positive for B/Victoria-lineage virus, and 36 tested positive for viruses of unknown subtype or lineage. A(H1N1)pdm09 viruses belonged to clade 6B, distinguished by a K163Q substitution, but remained antigenically similar to the A/California/07/2009-like vaccine strain, with an adjusted VE of 71% (95% confidence interval [CI], 58%-80%). Most B/Yamagata-lineage viruses (83%) clustered phylogenetically with the prior (ie, 2012-2013) season's B/Wisconsin/01/2010-like clade 3 vaccine strain, while only 17% clustered with the current (ie, 2013-2014) season's B/Massachusetts/02/2012-like clade 2 vaccine strain. The adjusted VE for B/Yamagata-lineage virus was 73% (95% CI, 57%-84%), with a lower VE obtained after partial calendar-time adjustment for clade-mismatched B/Wisconsin/01/2010-like virus (VE, 63%; 95% CI, 41%-77%), compared with that for clade-matched B/Massachusetts/02/2012-like virus (VE, 88%; 95% CI, 48%-97%). No A(H3N2) viruses clustered with the A/Texas/50/2012-like clade 3C.1 vaccine strain, and more than half were antigenically mismatched, but sparse data did not support VE estimation. CONCLUSIONS VE corresponded with antigenically conserved A(H1N1)pdm09 and lineage-matched B/Yamagata viruses with clade-level variation. Surveillance linking genotypic, phenotypic, and epidemiologic measures of vaccine-virus relatedness and effectiveness could better inform predictions of vaccine performance and reformulation.

BACKGROUND: Enterovirus D68 (EV-D68) has been detected infrequently and has not been associated with severe disease in Canada. In the early fall of 2014, following an unusual case increase in the United States, clusters of EV-D68 among children and some adults manifesting severe symptoms were reported in Canada. OBJECTIVE: To provide an initial epidemiological summary of pediatric cases hospitalized with EV-D68 in Canada. METHODS: A time-limited surveillance pilot was conducted collecting information on pediatric cases (less than 18 years of age) hospitalized with EV-D68 between September 1 and 30, 2014. RESULTS: In total, 268 cases were reported from Ontario (n=210), Alberta (n=45), and British Columbia (n=13). Of the 268 reported cases, 64.9% (n=174) were male; the sex difference was statistically significant (p

Typically, rates of resistance to various antibiotics in a given pathogen are assessed for a single drug at a time, in the setting of a particular type of infection. A more cohesive analysis is the drug resistance index, which incorporates resistance to multiple drugs for a given pathogen. The authors of this article developed a drug resistance index for Escherichia coli causing urinary tract infections in British Columbia., BACKGROUND: Drug resistance indexes (DRIs) quantify the cumulative impact of antimicrobial resistance on the likelihood that a given pathogen will be susceptible to antimicrobial therapy. OBJECTIVE: To derive a DRI for community urinary tract infections caused by Escherichia coli in British Columbia for the years 2007 to 2010, and to examine trends over time and across patient characteristics. METHODS: Indication-specific utilization data were obtained from BC PharmaNet for outpatient antimicrobial prescriptions linked to diagnostic information from physician payment files. Resistance data for E coli urinary isolates were obtained from BC Biomedical Laboratories (now part of LifeLabs Medical Laboratory Services). DRIs were derived by multiplying the rate of resistance to a specific antimicrobial by the proportional rate of utilization for that drug class and aggregating across drug classes. Higher index values indicate more resistance. RESULTS: Adaptive-use DRIs remained stable over time at approximately 18% (95% CI 17% to 18%) among adults ≥15 years of age and approximately 28% (95% CI 26% to 31%) among children

Using a test-negative design, the Canadian Sentinel Practitioner Surveillance Network (SPSN) assessed interim 2016/17 influenza vaccine effectiveness (VE) against dominant influenza A(H3N2) viruses considered antigenically matched to the clade 3C.2a vaccine strain. Sequence analysis revealed substantial heterogeneity in emerging 3C.2a1 variants by province and over time. Adjusted VE was 42% (95% confidence interval: 18–59%) overall, with variation by province. Interim virological and VE findings reported here warrant further investigation to inform potential vaccine reformulation.

To understand the epidemic resurgence of influenza due to the 2009 pandemic influenza A(H1N1) strain (A[H1N1]pdm09) during the 2013-2014 influenza season, we compared age-related cross-sectional estimates of seroprotection before the pandemic (during 2009) and after the pandemic (during 2010 and 2013) to subsequent surveillance-based, laboratory-confirmed incidence of influenza due to A(H1N1)pdm09 in British Columbia, Canada. Prepandemic seroprotection was negligible except for very old adults (defined as adults aged ≥ 80 years), among whom 80% had seroprotection. Conversely, postpandemic seroprotection followed a U-shaped distribution, with detection in approximately 35%-45% of working-aged adults but in ≥ 70% of very old adults and young children, excluding children aged

Objectives. We comprehensively assessed health care utilization in a population-based sample of homeless adults and matched controls under a universal health insurance system. Methods. We assessed health care utilization by 1165 homeless single men and women and adults in families and their age- and gender-matched low-income controls in Toronto, Ontario, from 2005 to 2009, using repeated-measures general linear models to calculate risk ratios and 95% confidence intervals (CIs). Results. Homeless participants had mean rates of 9.1 ambulatory care encounters (maximum = 141.1), 2.0 emergency department (ED) encounters (maximum = 104.9), 0.2 medical–surgical hospitalizations (maximum = 14.9), and 0.1 psychiatric hospitalizations per person-year (maximum = 4.8). Rate ratios for homeless participants compared with matched controls were 1.76 (95% CI = 1.58, 1.96) for ambulatory care encounters, 8.48 (95% CI = 6.72, 10.70) for ED encounters, 4.22 (95% CI = 2.99, 5.94) for medical–surgical hospitalizations, and 9.27 (95% CI = 4.42, 19.43) for psychiatric hospitalizations. Conclusions. In a universal health insurance system, homeless people had substantially higher rates of ED and hospital use than general population controls; these rates were largely driven by a subset of homeless persons with extremely high-intensity usage of health services.

Objectives. We identified predictors of emergency department (ED) use among a population-based prospective cohort of homeless adults in Toronto, Ontario. Methods. We assessed ED visit rates using administrative data from the Institute for Clinical Evaluative Sciences (2005–2009). We then used logistic regression to identify predictors of ED use. Frequent users were defined as participants with rates in the top decile (≥ 4.7 visits per person-year). Results. Among 1165 homeless adults, 892 (77%) had at least 1 ED visit during the study. The average rate of ED visits was 2.0 visits per person-year, whereas frequent users averaged 12.1 visits per person-year. Frequent users accounted for 10% of the sample but contributed more than 60% of visits. Predictors of frequent use in adjusted analyses included birth in Canada, higher monthly income, lower health status, perceived unmet mental health needs, and perceived external health locus of control from powerful others; being accompanied by a partner or dependent children had a protective effect on frequent use. Conclusions. Among homeless adults with universal health insurance, a small subgroup accounted for the majority of visits to emergency services. Frequent use was driven by multiple predisposing, enabling, and need factors.

The purpose of this study was to estimate the prevalence of mental health problems among a representative sample of homeless women with and without dependent children and determine if the effects of risk factors for mental health are modified by the presence of dependent children. Homeless women (n = 522) were recruited in 2004-2005 from shelters and meal programs in Toronto, Canada. Linear and logistic regression was performed to identify factors associated with mental health status. Poor mental health was associated with low perceived access to social support, physical/sexual assault in the past 12 months, presence of a chronic health condition, and presence of a drug use problem in the past month. Efforts to improve mental health in this population will need to address the associated problems of victimization, substance abuse, and lack of social supports.

Using a test-negative design, the Canadian Sentinel Practitioner Surveillance Network (SPSN) assessed interim 2015/16 vaccine effectiveness (VE) against influenza A(H1N1)pdm09 viruses. Adjusted VE showed significant protection of 64% (95% confidence interval (CI): 44–77%) overall and 56% (95%CI: 26–73%) for adults between 20 and 64 years-old against medically attended, laboratory-confirmed A(H1N1)pdm09 illness. Among the 67 A(H1N1)pdm09-positive specimens that were successfully sequenced, 62 (> 90%) belonged to the emerging genetic 6B.1 subclade, defined by S162N (potential gain of glycosylation) and I216T mutations in the haemagglutinin protein. Findings from the Canadian SPSN indicate that the 2015/16 northern hemisphere vaccine provided significant protection against A(H1N1)pdm09 illness despite genetic evolution in circulating viruses.

Using an integrated surveillance platform, we incorporated genetic, antigenic, and epidemiologic indicators to evaluate agent–host factors that contributed to low vaccine effectiveness during the 2014–2015 influenza season, including variation in the viral genome and negative effects of serial vaccination., Background. The 2014–2015 influenza season was distinguished by an epidemic of antigenically-drifted A(H3N2) viruses and vaccine components identical to 2013–2014. We report 2014–2015 vaccine effectiveness (VE) from Canada and explore contributing agent–host factors. Methods. VE against laboratory-confirmed influenza was derived using a test-negative design among outpatients with influenza-like illness. Sequencing identified amino acid mutations at key antigenic sites of the viral hemagglutinin protein. Results. Overall, 815/1930 (42%) patients tested influenza-positive: 590 (72%) influenza A and 226 (28%) influenza B. Most influenza A viruses with known subtype were A(H3N2) (570/577; 99%); 409/460 (89%) sequenced viruses belonged to genetic clade 3C.2a and 39/460 (8%) to clade 3C.3b. Dominant clade 3C.2a viruses bore the pivotal mutations F159Y (a cluster-transition position) and K160T (a predicted gain of glycosylation) compared to the mismatched clade 3C.1 vaccine. VE against A(H3N2) was −17% (95% confidence interval [CI], −50% to 9%) overall with clade-specific VE of −13% (95% CI, −51% to 15%) for clade 3C.2a but 52% (95% CI, −17% to 80%) for clade 3C.3b. VE against A(H3N2) was 53% (95% CI, 10% to 75%) for patients vaccinated in 2014-2015 only, significantly lower at −32% (95% CI, −75% to 0%) if also vaccinated in 2013–2014 and −54% (95% CI, −108% to −14%) if vaccinated each year since 2012–2013. VE against clade-mismatched B(Yamagata) viruses was 42% (95% CI, 10% to 62%) with less-pronounced reduction from prior vaccination compared to A(H3N2). Conclusions. Variation in the viral genome and negative effects of serial vaccination likely contributed to poor influenza vaccine performance in 2014–2015.

As elsewhere, few (

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.

Supportive housing, defined as subsidized housing in conjunction with site-based social services, may help improve the health and residential stability of highly disadvantaged individuals. This study examined changes in health status, quality of life, substance use, health care utilization, and residential stability among 112 homeless and vulnerably housed individuals who applied to a supportive housing program in Toronto, Canada, from December 2005 to June 2007. Follow-up interviews were conducted every 6 months for 18 months. Comparisons were made between individuals who were accepted into the program (intervention) and those who were wait-listed (usual care) using repeated-measures analyses. Individuals who were accepted into the housing program experienced significantly greater improvements in satisfaction with living situation compared with individuals in the usual care group (time, F(3,3,261) = 47.68, p

We undertook a synthesis of existing studies to re-evaluate the evidence on program mechanisms of intimate partner violence (IPV) universal screening and disclosure within a health care context by addressing how, for whom, and in what circumstances these programs work. Our review is informed by a realist review approach, which focuses on program mechanisms. Systematic, realist reviews can help reveal why and how interventions work and can yield information to inform policies and programs. A review of the scholarly literature from January 1990 to July 2010 identified 5046 articles, 23 of which were included in our study. We identified studies on 17 programs that evaluated IPV screening. We found that programs that took a comprehensive approach (i.e., incorporated multiple program components, including institutional support) were successful in increasing IPV screening and disclosure/identification rates. Four program components appeared to increase provider self-efficacy for screening, including institutional support, effective screening protocols, thorough initial and ongoing training, and immediate access/referrals to onsite and/or offsite support services. These findings support a multi-component comprehensive IPV screening program approach that seeks to build provider self-efficacy for screening. Further implications for IPV screening intervention planning and implementation in health care settings are discussed.

Objective To assess the accuracy of self-reported ambulatory care visits, emergency department (ED) encounters, and overnight hospitalizations in a population-based sample of homeless adults. Data Source Self-report survey data and administrative health care utilization databases. Study Design Self-reported health care use in the past 12 months was compared to administrative encounter records among 1,163 homeless adults recruited in 2004–2005 from shelters and meal programs in Toronto, Ontario. Data Extraction Methods Self-reported health care use was assessed using a structured face-to-face survey. Each participant was linked to administrative databases using a unique personal health number or their first name, last name, sex, and date of birth. Principal Findings The sensitivity of self-report for ambulatory care visits, ED encounters, and overnight hospitalizations was 89, 80, and 73 percent, respectively; specificity was 37, 83, and 91 percent. The mean difference between self-reported and documented number of encounters in the past 12 months was +1.6 for ambulatory care visits (95 percent CI = 0.4, 2.8), −0.6 for ED encounters (95 percent CI = −0.8, −0.4), and 0.0 for hospitalizations (95 percent CI = 0.0, 0.1). Conclusions Adults experiencing homelessness are quite accurate reporters of their use of health care, especially for ED encounters and hospitalizations.