Initial Results of the Québec Resilience Project (QRP): a Longitudinal and Representative Population-Based Study of Children's Development Prior to and During the COVID-19 Pandemic (2017-2022).

The COVID-19 pandemic instigated changes in almost all aspects of youth's life. While numerous studies have been implemented to understand how these changes are related to youth's development, few concerned large representative samples. This study introduces the methodology and initial results of the Quebec (Canada) Resilience Project (QRP), a representative longitudinal study. The QRP encompassed three phases: (a) 2017 census survey assessing school readiness in kindergarteners before the pandemic (n = 83,335, aged 6 years); (b) 2021 questionnaire study assessing family functioning during COVID-19-related lockdowns (n = 4524, aged 10 years); and (c) 2022 questionnaire survey assessing children's school performance and mental health post-lockdowns (n = 8217, aged 11 years). In total, 3871 children were assessed either by parents or teachers in the three phases. We explored factors associated with children school performance (maths, reading, and writing) and mental health (emotional, withdrawal, hyperactivity/impulsivity/inattention, and conduct problems symptoms). Population weights were estimated from census data to maintain the representativeness of the population. School readiness vulnerability in kindergarten and parental anxiety and depression during lockdowns were associated with both children's lower school performances and higher levels of all mental health symptoms post-lockdown. Loss in family income and parental difficulties in maintaining work-life balance during lockdowns were associated with children's lower school performance and higher levels of some mental health symptoms (emotional and hyperactivity/impulsivity/inattention) post-lockdown. The results underscore that pandemic-related disruptions were negatively associated with children's school performance, emphasizing the need for interventions in the school environment. Associations between pandemic-related disruptions and children mental health were less consistent yet emphasize the importance of parental mental health.