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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.

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.

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.

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.

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.

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

Studies in the 1970s and 1980s signaled concern that repeated influenza vaccination could affect vaccine protection. The antigenic distance hypothesis provided a theoretical framework to explain variability in repeat vaccination effects based on antigenic similarity between successive vaccine components and the epidemic strain. Areas covered: A meta-analysis of vaccine effectiveness studies from 2010-11 through 2014-15 shows substantial heterogeneity in repeat vaccination effects within and between seasons and subtypes. When negative effects were observed, they were most pronounced for H3N2, especially in 2014-15 when vaccine components were unchanged and antigenically distinct from the epidemic strain. Studies of repeated vaccination across multiple seasons suggest that vaccine effectiveness may be influenced by more than one prior season. In immunogenicity studies, repeated vaccination blunts the hemagglutinin antibody response, particularly for H3N2. Expert commentary: Substantial heterogeneity in repeated vaccination effects is not surprising given the variation in study populations and seasons, and the variable effects of antigenic distance and immunological landscape in different age groups and populations. Caution is required in the interpretation of pooled results across multiple seasons, since this can mask important variation in repeat vaccination effects between seasons. Multi-season clinical studies are needed to understand repeat vaccination effects and guide recommendations.

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.

The 2014/15 influenza season to date in Canada has been characterised by predominant influenza A(H3N2) activity. Canada's Sentinel Physician Surveillance Network (SPSN) assessed interim vaccine effectiveness (VE) against medically attended, laboratory-confirmed influenza A(H3N2) infection in January 2015 using a test-negative case-control design. Of 861 participants, 410 (48%) were test-positive cases (35% vaccinated) and 451 (52%) were test-negative controls (33% vaccinated). Among test-positive cases, the majority (391; 95%) were diagnosed with influenza A, and of those with available subtype information, almost all influenza A viruses (379/381; 99%) were A(H3N2). Among 226 (60%) A(H3N2) viruses that were sequenced, 205 (91%) clustered with phylogenetic clade 3C.2a, considered genetically and antigenically distinct from the 2014/15 A/Texas/50/2012(H3N2)-like clade 3C.1 vaccine reference strain, and typically bearing 10 to 11 amino acid differences from the vaccine at key antigenic sites of the haemagglutinin protein. Consistent with substantial vaccine mismatch, little or no vaccine protection was observed overall, with adjusted VE against medically attended influenza A(H3N2) infection of ?8% (95% CI: ?50 to 23%). Given these findings, other adjunct protective measures should be considered to minimise morbidity and mortality, particularly among high-risk individuals. Virus and/or host factors influencing this reduced vaccine protection warrant further in-depth investigation. .

This case series describes morbilliform and other rash presentations among schoolchildren during a March 2014 outbreak of influenza-like illness (ILI) in British Columbia, Canada. Multiplex nucleic acid testing of nasopharyngeal specimens and paired serologic investigations identified that influenza B, characterized as B/Massachusetts/02/2012-like (Yamagata-lineage), was the only viral aetiology and most likely cause of ILI and rash. An association between influenza B and rash has been described infrequently elsewhere, and not previously in North America. Influenza B should be considered in the differential diagnosis of febrile exanthem. Evaluation of the nature, incidence and contributing agent–host–environment interactions, and immunologic mechanisms to possibly explain influenza-associated rash is warranted.

The 2013/14 influenza season to date in Canada has been characterised by predominant (90%) A(H1N1)pdm09 activity. Vaccine effectiveness (VE) was assessed in January 2014 by Canada's sentinel surveillance network using a test-negative case-control design. Interim adjusted-VE against medically-attended laboratory-confirmed influenza A(H1N1)pdm09 infection was 74% (95% CI: 58-83). Relative to vaccine, A(H1N1)pdm09 viruses were antigenically similar and genetically well conserved, with most showing just three mutations across the 50 amino acids comprising antigenic sites of the haemagglutinin protein. .

Background Homeless persons experience a high burden of health problems; yet, they face significant barriers in accessing health care. Less is known about unmet needs for care among vulnerably housed persons who live in poor-quality or temporary housing and are at high risk of becoming homeless. The objectives of this study were to examine the prevalence of and factors associated with unmet needs for health care in a population-based sample of homeless and vulnerably housed adults in three major cities within a universal health insurance system. Methods Participants were recruited at shelters, meal programs, community health centers, drop-in centers, rooming houses, and single room occupancy hotels in Vancouver, Toronto, and Ottawa, Canada, throughout 2009. Baseline interviews elicited demographic characteristics, health status, and barriers to health care. Logistic regression was used to identify factors associated with self-reported unmet needs for health care in the past 12 months. Results Of the 1,181 participants included in the analysis, 445 (37%) reported unmet needs. In adjusted analyses, factors associated with a greater odds of reporting unmet needs were having employment in the past 12 months (AOR = 1.40, 95% CI = 1.03–1.91) and having ≥3 chronic health conditions (AOR = 2.17, 95% CI = 1.24–3.79). Having higher health-related quality of life (AOR = 0.21, 95% CI = 0.09–0.53), improved mental (AOR = 0.97, 95% CI = 0.96–0.98) or physical health (AOR = 0.98, 95% CI = 0.96–0.99), and having a primary care provider (AOR = 0.63, 95% CI = 0.46–0.85) decreased the odds of reporting unmet needs. Conclusions Homeless and vulnerably housed adults have a similar likelihood of experiencing unmet health care needs. Strategies to improve access to primary care and reduce barriers to accessing care in these populations are needed.

To compare length of stay and total hospital costs among patients admitted to hospital under the care of family physicians who were their usual health care providers in the community (group A) and patients admitted to the same inpatient service under the care of family physicians who were not their usual health care providers (group B).Retrospective observational study.A large urban hospital in Vancouver, BC.All adult admissions to the family practice inpatient service between April 1, 2006, and June 30, 2008.Ratio of length of stay to expected length of stay and total hospital costs per resource intensity weight unit. Multivariate linear regression was performed to determine the effect of admitting group (group A vs. group B) on the natural logarithm transformations of the outcomes.The median acute length of stay was 8.0 days (interquartile range [IQR] 4.0 to 13.0 days) for group A admissions and 8.0 days (IQR 4.0 to 15.0 days) for group B admissions. The median (IQR) total hospital costs were $6498 ($4035 to $11,313) for group A admissions and $6798 ($4040 to $12,713) for group B admissions. Aftera djustment for patient characteristics, patients admitted to hospital under the care of their own family physicians did not significantly differ in terms of acute length of stay to expected length of stay ratio (percent change 0.6%, P = .942)or total hospital costs per resource intensity weight unit (percent change -2.0%, P = .722) compared with patients admitted under the care of other family physicians.These findings suggest that having networks of family physicians involved in hospital care for patients is not less efficient than having family physicians provide care for their own patients.

To date, social epidemiology research has largely been restricted to the description of health disparities and their association with social gradients. Rarely do social epidemiologists expand upon these general-level associations and begin to examine the causal pathways linking social disparities to health. This research approach presents numerous challenges for public health practitioners who attempt to integrate social epidemiology research into policies and programs, as intervention on the identified social gradients is difficult and may divert efforts from more productive options. Furthermore, social epidemiology research is seldom accessible to public health practitioners in a form that is applicable to practice and adaptable to the local context. In order to generate research that can be translated into action to improve health, social epidemiology must progress from providing descriptions at the general level and begin to understand mechanisms leading to health outcomes. The purpose of this chapter is to discuss how social epidemiologists can produce such evidence and ensure that their research is more relevant to public health policy and practice. This chapter will also examine the challenges associated with integrating social epidemiology research into practice and offer guidance for how a social epidemiology research agenda can be implemented.

While substantial research has demonstrated the poor health status of homeless populations, the health status of vulnerably housed individuals is largely unknown. Furthermore, few longitudinal studies have assessed the impact of housing transitions on health. The health and housing in transition (HHiT) study is a prospective cohort study that aims to track the health and housing status of a representative sample of homeless and vulnerably housed single adults in three Canadian cities (Toronto, Ottawa, and Vancouver). This paper discusses the HHiT study methodological recruitment strategies and follow-up procedures, including a discussion of the limitations and challenges experienced to date. Participants (n = 1,192) were randomly selected at shelters, meal programmes, community health centres, drop-in centres, rooming houses, and single-room occupancy hotels from January to December 2009 and are being re-interviewed every 12 months for a 2-year period. At baseline, over 85% of participants reported having at least one chronic health condition, and over 50% reported being diagnosed with a mental health problem. Our findings suggest that, regardless of housing status, participants had extremely poor overall health.

Background Despite experiencing a disproportionate burden of acute and chronic health issues, many homeless people face barriers to primary health care. Most studies on health care access among homeless populations have been conducted in the United States, and relatively few are available from countries such as Canada that have a system of universal health insurance. We investigated access to primary health care among a representative sample of homeless adults in Toronto, Canada. Methods Homeless adults were recruited from shelter and meal programs in downtown Toronto between November 2006 and February 2007. Cross-sectional data were collected on demographic characteristics, health status, health determinants and access to health care. We used multivariable logistic regression analysis to investigate the association between having a family doctor as the usual source of health care (an indicator of access to primary care) and health status, proof of health insurance, and substance use after adjustment for demographic characteristics. Results Of the 366 participants included in our study, 156 (43%) reported having a family doctor. After adjustment for potential confounders and covariates, we found that the odds of having a family doctor significantly decreased with every additional year spent homeless in the participant’s lifetime (adjusted odds ratio [OR] 0.91, 95% confidence interval [CI] 0.86–0.97). Having a family doctor was significantly associated with being lesbian, gay, bisexual or transgendered (adjusted OR 2.70, 95% CI 1.04–7.00), having a health card (proof of health insurance coverage in the province of Ontario) (adjusted OR 2.80, 95% CI 1.61–4.89) and having a chronic medical condition (adjusted OR 1.91, 95% CI 1.03–3.53). Interpretation Less than half of the homeless people in Toronto who participated in our study reported having a family doctor. Not having a family doctor was associated with key indicators of health care access and health status, including increasing duration of homelessness, lack of proof of health insurance coverage and having a chronic medical condition. Increased efforts are needed to address the barriers to appropriate health care and good health that persist in this population despite the provision of health insurance.