Dr. Kate Zinszer, from the Université de Montréal, and her EnCORE study team have released interim non-peer reviewed results suggesting a marked increase in seroprevalence among Montreal children aged 2-17 years-old in recent months. They found that 3.3% of participants had antibodies to SARS-CoV-2 in October-November 2020, whereas 8.9% had antibodies between February-April 2021, with the highest seroprevalence in lower socioeconomic areas. Most parents surveyed reported that they are likely to get their child vaccinated for COVID-19 as soon as vaccines are available.

Key results:

  • Percentage of children with antibodies recognizing SARS-CoV-2 has increased from 3.3% in October-November 2020 to 8.9% between February and April 2021.
  • Geographical differences in positive cases were noted, with lower socioeconomic areas (Montreal North and Mercier-Hochelaga-Maisonneuve) having the highest seroprevalence.
  • Most parents (86%) reported they are likely to get their child vaccinated for COVID-19 as soon as this option is available, however 33% of parents from racialized communities indicated they would be reticent to vaccinate their children.

The EnCORE cohort is comprised of 1901 children (49% female and 51% male, sex determined at birth), aged 2- to 17- years-old, with 423 in daycare, 853 in elementary school and 625 in high school. Blood samples from 1632 children aged 2- to 17- years-old from Montreal were collected via finger prick (dried blood spot) and analyzed for the presence of antibodies recognizing SARS-CoV-2, suggesting they had previously been infected. The average number of children with antibodies was 5.8% (6.9% for female and 4.9% for male participants). The authors of this study noted that the seroprevalence increased with time, from 3.3% in Oct-Nov 2020 to 8.9% during Feb-Apr 2021. Also, higher seroprevalence was noted for older children: 5.0% for children in daycares and 5.6% for children in elementary schools versus 6.7% for children in high schools.

Participants were recruited from schools and daycares in four areas of Montreal with distinct socioeconomic and population differences: the Plateau Mont-Royal, Montreal North, West island, and Mercier-Hochelaga-Maisonneuve (HOMA). In the preliminary results, geographical differences were noted, with the lowest seroprevalence recorded in West island (4.8%), the highest socioeconomic area studied, and the highest seroprevalence in Montreal North (7.3%), the area with the lowest socioeconomic status.

Parents completed an online questionnaire about their child’s health, including emotional and mental health, as well as household information. The majority of the parents surveyed, (340 out of 395 or 86%) reported they are likely to get their child vaccinated for COVID-19 as soon as a vaccine is available for children. About a third (35%) of parents from racialized communities indicated they would be reticent to vaccinate their children.

 

Their complete preliminary results, which have not been peer reviewed yet, can be found here.

Our news release about these results can be found here.