Infection-induced seroconversion and seroprevalence of SARS-CoV-2 among a cohort of children and youth in Montreal, Canada.

The EnCORE study is a prospective serology study of SARS-CoV-2 in a cohort of children from Montreal, Canada. Based on data from our fourth round of data collection (May-October 2022), we estimated SARS-CoV-2 seroprevalence and seroconversion. Using multivariable regression, we identified factors associated with seroconversion. Our results show that previously seronegative children were approximately 9-12 times more likely to seroconvert during the early Omicron-dominant period compared to pre-Omicron rounds. Unlike the pre-Omicron rounds, the adjusted rate of seroconversion among 2- to 4-year-olds was higher than older age groups. As seen previously, higher seroconversion rates were associated with ethnic/racial minority status.

Portrait of Montréal healthcare workers infected with SARS-CoV-2 during the first wave of the pandemic: a cross-sectional study.

OBJECTIVES: During the first wave of COVID-19 in Québec, healthcare workers (HCWs) represented 25% of the cases in Montréal. A study was conducted to describe SARS-CoV-2-infected HCWs in Montréal, and certain workplace and household characteristics. Secondary objectives included estimating the associations between having had access to personal protective equipment (PPE) and training, and following self-isolation recommendations, and certain sociodemographic and workplace characteristics. METHODS: A cross-sectional study was conducted, based on a stratified random sample, among Montréal HCWs who tested positive for SARS-CoV-2 between March and July 2020. A total of 370 participants answered a telephone-administered questionnaire. Descriptive statistics were conducted, followed by log binomial regressions to estimate the associations. RESULTS: Study participants were mostly female (74%), born outside of Canada (65%), and identified as Black, Indigenous, and People of Colour (BIPOC; 63%). In terms of healthcare positions, most were orderlies (40%) or registered nurses (20%). Half (52%) of the participants reported having had insufficient access to PPE and 30% reported having received no training related to SARS-CoV-2 infection prevention, with large proportions being BIPOC women. Working evening or night shifts decreased chances of having had sufficient access to PPE (OR 0.50; 0.30-0.83). CONCLUSION: This study describes the profile of the HCWs who were infected during the first wave of the pandemic in Montréal. Recommendations include collecting comprehensive sociodemographic data on SARS-CoV-2 infections and ensuring equitable access to infection prevention and control training and PPE during health crises, particularly those at highest risk of exposure.

RéSUMé: OBJECTIFS: Lors de la première vague de la COVID-19 au Québec, les travailleurs de la santé (TS) représentaient 25 % des cas à Montréal. Une étude a été menée pour décrire les TS infectés par le SRAS-CoV-2 à Montréal, ainsi que certaines caractéristiques liées au travail et au ménage. Les objectifs secondaires visaient à estimer les associations entre le fait d'avoir eu accès à un équipement de protection individuelle (EPI) et à une formation, ainsi que la capacité de suivre les recommandations d'auto-isolement et différentes caractéristiques sociodémographiques et du lieu de travail. MéTHODOLOGIE: Une étude transversale a été menée, sur la base d'un échantillon aléatoire stratifié, parmi les TS de Montréal qui ont été testés positifs pour le SRAS-CoV-2 entre mars et juillet 2020. Un total de 370 participants a répondu à un questionnaire administré par téléphone. Des statistiques descriptives ont été réalisées, suivies de régressions log binomiales pour estimer les associations. RéSULTATS: Les participants étaient en majorité des femmes (74 %), nés à l'extérieur du Canada (65 %) et s'identifiaient comme des personnes Noires, des Autochtones et des personnes de couleur (BIPOC; 63 %). En termes d'emploi dans le système de santé, 40 % étaient des préposés aux bénéficiaires et 20 % des infirmières cliniciennes. La moitié (52 %) des participants ont déclaré ne pas avoir eu un accès suffisant à l'EPI et 30 % ont déclaré n'avoir reçu aucune formation liée à la prévention des infections SRAS-CoV-2, une grande partie d'entre eux étant des femmes BIPOC. Le fait de travailler le soir ou la nuit diminuait les chances d'avoir un accès suffisant aux EPI (OR 0,50; 0,30­0,83). CONCLUSION: Cette étude décrit le profil des travailleurs de santé qui ont été infectés lors de la première vague de la pandémie à Montréal. Les recommandations comprennent la collecte de données sociodémographiques complètes et de s'assurer de fournir de l'EPI et des formations en prévention et contrôle des infections pendant les crises sanitaires, en particulier pour les personnes les plus à risque d'exposition.

Feminizing hormone therapy in a Canadian cohort of transgender women with and without HIV.

BACKGROUND: Potential bidirectional drug-drug interactions between feminizing hormone therapy (FHT) and antiretroviral therapy (ART) are of concern for trans women with HIV and their healthcare providers. This study aimed to characterize patterns of FHT and ART among trans women with HIV and to compare serum hormone levels to trans women without HIV. METHODS: Charts of trans women were reviewed at seven HIV primary care or endocrinology clinics in Toronto and Montreal from 2018 to 2019. ART regimens, FHT use, serum estradiol, and serum testosterone levels were compared on the basis of HIV status (positive, negative, missing/unknown). RESULTS: Of 1495 trans women, there were 86 trans women with HIV, of whom 79 (91.8%) were on ART. ART regimens were most commonly integrase inhibitor-based (67.4%), many boosted with ritonavir or cobicistat (45.3%). Fewer (71.8%) trans women with HIV were prescribed FHT, compared to those without HIV (88.4%) and those with missing/unknown status (90.2%, p < 0.001). Among trans women on FHT with recorded serum estradiol (n = 1153), there was no statistical difference in serum estradiol between those with HIV (median: 203 pmol/L, IQR: 95.5, 417.5) and those with negative (200 mol/L [113, 407]) or missing/unknown HIV status (227 pmol/L [127.5, 384.5) (p = 0.633). Serum testosterone concentrations were also similar between groups. CONCLUSIONS: In this cohort, trans women with HIV were prescribed FHT less often than trans women with negative or unknown HIV status. There was no difference in serum estradiol or testosterone levels of trans women on FHT regardless of HIV status, providing reassurance regarding potential drug-drug interactions between FHT and ART.

Pre-Omicron seroprevalence, seroconversion, and seroreversion of infection-induced SARS-CoV-2 antibodies among a cohort of children and teenagers in Montréal, Canada.

OBJECTIVES: To use serological testing to assess the pre-Omicron seroprevalence, seroconversion, and seroreversion of infection-induced SARS-CoV-2 antibodies in children and adolescents in Montréal, Canada. DESIGN: This analysis is from a prospective cohort study of children aged 2-17 years (at baseline) that included blood spots for antibody detection. The serostatus of participants was determined by enzyme-linked immunosorbent assays using the receptor-binding domain from the spike protein and the nucleocapsid protein as antigens. We estimated seroprevalence, seroconversion rates, and the likelihood of seroreversion at 6 months and 1 year. RESULTS: The baseline (October 2020 to April 2021) seroprevalence was 5.8% (95% confidence interval [CI] 4.8-7.1), which increased to 10.5% (May to September 2021) and 11.0% (November 2021 to March 2022) for the respective follow-ups (95% CI 8.6-12.7; 95% CI 8.8-13.5). The crude rate of seroconversion over the study period was 12.8 per 100 person-years (95% CI 11.0-14.7). The adjusted hazard rates of seroconversion by child characteristics showed higher rates in children who were female, whose parent identified as a racial or ethnic minority, and in households with incomes in the lowest tercile of our study population. The likelihood of remaining seropositive at 6 months was 68% (95% CI 60-77%) and dropped to 42% (95% CI 32-56%) at 1 year. CONCLUSION: Serological studies continue to provide valuable contributions for infection prevalence estimates and help us better understand the dynamics of antibody levels after infection.

Seroprevalence of SARS-CoV-2 Antibodies Among Children in School and Day Care in Montreal, Canada.

Importance: Quebec prioritized in-person learning after the first wave of the COVID-19 pandemic, with school closures being implemented temporarily in selected schools or in hot-spot areas. Quebec's decision to keep most schools open was controversial, especially in Montreal, which was the epicenter of Canada's first and second waves; therefore, understanding the extent to which children were infected with SARS-CoV-2 provides important information for decisions about school closures. Objective: To estimate the seroprevalence of SARS-CoV-2 antibodies in children and teenagers in 4 neighborhoods of Montreal, Canada. Design, Setting, and Participants: This cohort study (the Enfants et COVID-19: Étude de séroprévalence [EnCORE] study) enrolled a convenience sample of children aged 2 to 17 years between October 22, 2020, and March 22, 2021, in Montreal, Canada. Exposures: Potential exposure to SARS-CoV-2. Main Outcomes and Measures: The main outcome was seroprevalence of SARS-CoV-2 antibodies, collected using dried blood spots (DBSs) and analyzed with a research-based enzyme-linked immunosorbent assay (ELISA). Parents also completed an online questionnaire that included questions on self-reported COVID-19 symptoms and tests, along with sociodemographic questions. Results: This study included 1632 participants who provided a DBS sample from 30 day cares, 22 primary schools, and 11 secondary schools. The mean (SD) age of the children who provided a DBS sample was 9.0 (4.4) years; 801 (49%) were female individuals, with 354 participants (22%) from day cares, 725 (44%) from primary schools, and 553 (34%) from secondary schools. Most parents had at least a bachelor's degree (1228 [75%]), and 210 (13%) self-identified as being a racial or ethnic minority. The mean seroprevalence was 5.8% (95% CI, 4.6%-7.0%) but increased over time from 3.2% (95% CI, 0.7%-5.8%) in October to November 2020 to 8.4% (95% CI, 4.4%-12.4%) in March to April 2021. Of the 95 children with positive SARS-CoV-2 antibody results, 78 (82%) were not tested or tested negative with reverse transcription-polymerase chain reaction (RT-PCR) testing, and all experienced mild (49 [52%]) or no clinical symptoms (46 [48%]). The children of parents who self-identified as belonging to a racial and ethnic minority group were more likely to be seropositive compared with children of White parents (adjusted seroprevalence ratio, 1.9; 95% CI, 1.1-2.6). Conclusions and Relevance: These results provide a benchmark of the seroprevalence status in Canadian children. The findings suggest that there was more transmission occurring in children compared with what was being detected by RT-PCR, although children experienced few or mild symptoms. It will be important to continue monitoring the serological status of children, particularly in the context of new COVID-19 variants of concern and in the absence of mass vaccination campaigns targeting young children.

Seroprevalence of anti-SARS-CoV-2 antibodies among school and daycare children and personnel: protocol for a cohort study in Montreal, Canada.

INTRODUCTION: Further evidence is needed to understand the contribution of schools and daycares for the spread of COVID-19 in the context of diverse transmission dynamics and continually evolving public health interventions. The Enfants et COVID-19: Étude de séroprévalence (EnCORE) study will estimate the seroprevalence and seroconversion of SARS-CoV-2 among school and daycare children and personnel. In addition, the study will examine associations between seroprevalence and sociodemographic characteristics and reported COVID-19 symptoms and tests, and investigates changes in health, lifestyle and well-being outcomes. METHODS AND ANALYSIS: This study includes children and personnel from 62 schools and daycares in four neighbourhoods in Montreal, Canada. All children aged 2-17 years attending one of the participating schools or daycares and their parents are invited to participate, as well as a sample of personnel members. Participants respond to brief questionnaires and provide blood samples, collected via dried blood spot, at baseline (October 2020-March 2021) and follow-up (May-June 2021). Questionnaires include sociodemographic and household characteristics, reported COVID-19 symptoms and tests, potential COVID-19 risk factors and prevention efforts and health and lifestyle information. Logistic regression using generalised estimating equations will be used to estimate seroprevalence and seroconversion, accounting for school-level clustering. ETHICS AND DISSEMINATION: This study was approved by the research ethics boards of the Université de Montréal (CERSES) and the Centre Hospitalier Universitaire Sainte-Justine. Results will contribute to our knowledge about SARS-CoV-2 transmission in schools and daycares and will be made available to study participants and their families, school and public health decision-makers and the research community.