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

Round 4: Preliminary Results, ENCORE – Children and COVID-19 Montreal seroprevalence study (May – September 2022).

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 58% of young children and teens had infection-acquired antibodies between May and September 2022. Moreover, 38% of the cohort had received a positive COVID-19 diagnosis since January 2022, during the Omicron era. The results, in a report to participants and their parents, are preliminary and have not been peer-reviewed.

Key Findings:

  • Overall seroprevalence, or the proportion of children with either infection-acquired antibodies or vaccine-induced antibodies, was 96.1%.
  • Infection-acquired seroprevalence between May 2022 to September 2022 was highest in kids ages 2-4 years (74.3%), followed by ages 12-19 (59.2%) and ages 5-11 years (51.9%).
  • Those 12- to 19-years-old were the most vaccinated: 95% had two doses or more. 80% of 5- to 11-year-olds and 0% of 2- to 4-year-olds had two or more doses.
  • With regard to the psycho-social impacts of COVID-19 on children:
    • 46% of parents were concerned about their child’s lack of social connections;
    • 46% of parents were concerned about their child’s mental and emotional health;
    • 38% of children were experiencing difficulties with emotions, concentration, behavior, or relationships, as reported by their parents.
    • Adolescents reported facing mental health issues including fatigue (52%), restlessness (35%), anxiety (32%), irritability (33%), and distraction/difficulty focusing (27%).
  • Parents (50%) and some adolescents (34%) strongly agreed that a vaccine passport was a good strategy to encourage people to get vaccinated. Similarly, more parents (22%) than adolescents (13%) strongly agreed that mask-wearing should be mandatory in primary and secondary schools.

921 children and adolescents participated in the study questionnaires – 15% were between the ages of 2 and 4, 48% were between 5 and 11 years old, and 37% were 12- to 17- years-old; 709 children and adolescents participated in the serological testing. The samples were collected between May and September 2022 in Montreal, coinciding with the 7th pandemic wave in Quebec, which was dominated by Omicron variants.