Parental decisions regarding the vaccination of children and adolescents against SARS-CoV-2 from 2020 to 2023: A descriptive longitudinal study of parents and children in Montreal, Canada.

Background: Given the growing evidence on the benefits of hybrid immunity, continued monitoring of vaccine uptake is warranted, particularly of socio-demographic subgroups with early vaccine hesitancy. Racial/ethnic and lower income groups experienced a high infection incidence, but few studies account for the child's history of SARS-CoV-2 infection on the parent's decision to vaccinate their child.

Methods: EnCORE is a SARS-CoV-2 pediatric cohort study comprising five rounds of data collection from 2020 to 2023, with parental questionnaires at each round.

Omicron incidence and seroprevalence among children in Montreal, Canada, in early 2023: final results from the longitudinal EnCORE serology study.

Since early 2022, routine testing for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) based on symptoms and exposure history has largely ceased in Canada. Consequently, seroprevalence studies, particularly longitudinal studies, have become critical for monitoring the rate of incident SARS-CoV-2 infections and the proportion of the population with evidence of immunity. EnCORE is a longitudinal SARS-CoV-2 seroprevalence study comprising five rounds of serology testing from October 2020 to June 2023, in a sample of 2- to 17-year-olds (at baseline), recruited from daycares and schools in four neighbourhoods of Montreal, Canada.

SARS-CoV-2 seroprevalence and mental health of school staff: a cross-sectional study of schools from four areas of Montreal, Quebec in 2021.

Objectives: To assess the seroprevalence of infection-acquired SARS-CoV-2 and the mental health of school/daycare staff in the months after reopening of schools in Montreal, Quebec (Canada) in the Fall of 2020 and whether these varied by school and participant characteristics.

Design: A cross-sectional design based on a convenience sample of schools/daycares and staff was used as the originally planned longitudinal design was no longer feasible due to obstacles in recruitment, for example, teacher's strike.

Setting: Forty-nine schools/daycares in four Montreal neighbourhoods from March to October 2021.

Generalizability of anti-SARS-CoV-2 seroprevalence estimates to the Montréal pediatric population: a comparison between two weighting methods.

Seroprevalence studies on SARS-CoV-2 infections have been often based on study populations with non-random and non-representative samples, limiting the generalizability of their results. In this study, we investigated the representativity and the generalizability of the baseline (collected from October 16th, 2020, to April 18th, 2021) estimate of a pediatric seroprevalence study based in Montréal. We compared the change in the estimates of seroprevalence for two different weighting methods: marginal standardization and raking.

Mental Health Hospitalizations in Canadian Children, Adolescents, and Young Adults Over the COVID-19 Pandemic.

Importance: The COVID-19 pandemic resulted in multiple socially restrictive public health measures and reported negative mental health impacts in youths. Few studies have evaluated incidence rates by sex, region, and social determinants across an entire population.

Objective: To estimate the incidence of hospitalizations for mental health conditions, stratified by sex, region, and social determinants, in children and adolescents (hereinafter referred to as youths) and young adults comparing the prepandemic and pandemic-prevalent periods.