This is a summary, written by members of the CITF Secretariat, of:

Round 5: Preliminary Results, ENCORE – Children and COVID-19 Montreal seroprevalence study (February – June 2023).

The results and/or conclusions contained in the research do not necessarily reflect the views of all CITF members.

The latest results from the CITF-funded EnCORE study, led by Dr. Kate Zinszer (Université de Montréal), looking at seroprevalence among children and adolescents in Montreal found that 79.4% of young children and teens had infection-acquired antibodies between February and June 2023. Overall, 13% of the cohort had received a positive SARS-CoV-2 test result between September 2022 and June 2023. The results, in a report to participants and their parents, are preliminary and have not been peer reviewed.

Key findings:

  • Overall seroprevalence (meaning the proportion of children/adolescents with either infection-acquired antibodies or vaccine-induced antibodies) was 99.4%.
  • Infection-acquired seroprevalence between February 2023 and June 2023 was highest in adolescents aged 12-19 years (82.2%), followed by children aged 2-4 (79.4%) and aged 5-11 years (76.3%).
  • Those 12- to 19-years-old were the most vaccinated: 94% had two doses or more. 80% of 5- to 11-year-olds and 21% of 2- to 4-year-olds had two or more doses.
  • The psychosocial impacts of COVID-19 on children and adolescents included these aspects:
    • 28% of parents were concerned about their child’s lack of social connection,
    • 39% of parents were concerned about their child’s mental and emotional health,
    • 41% of children were experiencing difficulties with emotions, concentration, behaviour, or relationships, as reported by their parents, and
    • Adolescents reported facing mental health issues including tiredness (60%), restlessness (46%), anxiety (39%), irritability (32%), and distraction/difficulty focusing (32%).
  • 34% of parents and 29% of adolescents strongly agreed that a COVID-19 vaccination requirement for participation in extracurricular activities would encourage people to get their children vaccinated.
  • 34% of parents and 26% of adolescents strongly agreed that mask-wearing should be mandatory in primary and secondary schools during outbreaks.

628 children and adolescents participated in the study questionnaires: 8% were between the ages of 2 and 4, 47% were between 5 and 11 years old, and 45% were between 12 and 19 years old. 505 children and adolescents participated in the serological testing. The samples were collected between February and June 2023 in Montreal.