Increased Mask Use and Fewer Gatherings Associated with Lower SARS-CoV-2 Seropositivity Among Young School-Age Children (preprint)

Background: The incidence of COVID-19 in children, defined by RT-PCR, is relatively low. Paediatric SARS-CoV-2 seropositivity studies may better estimate a history of COVID-19 in children and thus facilitate understanding of transmission risk factors. Methods: We invited 8-13-year-old children from the Edmonton area to participate in a longitudinal SARS-CoV-2 seropositivity study. At baseline, parents completed a questionnaire regarding their child’s frequency of behaviours to prevent SARS-CoV-2 transmission and exposure (e.g. wearing masks and avoiding gatherings of > 10 people) from March 2020 in addition to measurement of their child’s SARS-CoV-2 nucleocapsid IgG levels (Abbott Architect). IgG≥0·8 were considered likely seropositive. We present the interim results from the first 2 months of the study (August to October 2020) examining predictors of being likely seropositive. Findings: We recruited 565 children with a mean age of 10·5 years (SD 1·6). None reported a positive SARS-CoV-2 RT-PCR result prior to recruitment. Nine children (1·6%) were likely seropositive. Children who did not wear a mask (never, rarely, occasionally) had a 4·2% (5/118) prevalence of being likely seropositive versus 0·9% (4/423) likely seropositive for children who often or always wore their mask (p<0·05). We found a significant interaction between mask use and gathering attendance in multivariate logistic regression. Children had 9·7 increased odds (95%CI 2·4, 38·9; p=0·001) of being likely seropositive for each gathering attended while not wearing a mask. Children had 1·02 increased odds (95%CI 1·0, 1·04; p=0·007) of being likely seropositive for each gathering attended while wearing a mask. Interpretation: SARS-CoV-2 seropositivity in a general population of children is low. Our preliminary data support the use of masks for children in gatherings to prevent infection. Funding Statement: This research was funded by the Government of Alberta (AH-FP17). The CHILD study Edmonton is funded by the Women’s and Children Health Research Institute and AllerGen NCE. The CHILD study was established by a grant from the Canadian Institute for Health Research (CIHR) and the AllerGen NCE. APrON was established by a grant from the Alberta Heritage Foundation for Medical Research and is maintained by a grant from the Alberta Children’s Hospital Foundation. Declaration of Interests: The authors declare that they have no conflicts of interest Ethics Approval Statement: Informed consent was obtained from all parents with assent from all children. The study was approved by the University of Alberta Research Ethics Board (PRO00102477).