Pre- versus post-COVID-19 pandemic comparison of kindergarten teacher-reported child development in multiple Canadian jurisdictions

Little is known so far about the impact of the COVID-19 pandemic on young children. We assessed the effect of the pandemic on pre-existing developmental trends in this population-level, repeated cross-sectional cohort design study of child development at school entry, measured with the kindergarten teacher-completed Early Development Instrument (EDI) in the 10 years prior to the onset of the COVID-19 pandemic and two years after. Individual EDI data for 913,739 children with individual EDI records were aggregated to 1398 neighbourhoods in 8 of Canada's 13 provinces and territories and grouped into four time intervals (three pre-pandemic and one post-pandemic) including all jurisdictions. The COVID-19 pandemic was the main exposure, and overall vulnerability on the EDI (scoring below normative threshold in one or more of the 5 developmental domains) was the primary outcome. Demographic (e.g., age) and neighbourhood-level socioeconomic (SES) characteristics were investigated as potential modifiers- specifically, whether poverty and COVID-19 suggested a double jeopardy effect. Latent growth curve models with structured residuals were used to quantify whether post-COVID-19 vulnerability rates deviated from the pre-COVID-19 trajectory. Overall vulnerability rates were increasing by 0.39 % per year prior to the onset of the pandemic. On average, post-COVID-19 developmental vulnerability rates did not deviate from this pre-COVID-19 trajectory. Demographic variables predicted post-COVID-19 deviations, whereas neighbourhood SES did not. However, neighbourhood SES moderated the effects of some demographic variables. As society continues to grapple with the consequences of the COVID-19 pandemic impact, these results underscore the continuing need of monitoring child development and education trends.