Age-dependent seroprevalence of SARS-CoV-2 antibodies in school-aged children from areas with low and high community transmission

Abstract

It is not yet clear to what extent SARS-CoV-2 infection rates in children reflect community transmission, nor whether infection rates differ between primary schoolchildren and young teenagers. A cross-sectional serosurvey compared the SARS-CoV2 attack-rate in a sample of 362 children recruited from September 21 to October 6, 2020, in primary (ages 6–12) or lower secondary school (ages 12–15) in a municipality with low community transmission (Pelt) to a municipality with high community transmission (Alken) in Belgium. Children were equally distributed over grades and regions. Blood samples were tested for the presence of antibodies to SARS-CoV-2 with an enzyme-linked immunosorbent assay. We found anti-SARS-CoV-2 antibodies in 4.4% of children in the low transmission region and in 14.4% of children in the high transmission region. None of the primary schoolchildren were seropositive in the low transmission region, whereas the seroprevalence among primary and secondary schoolchildren did not differ significantly in the high transmission region. None of the seropositive children suffered from severe disease. Children who were in contact with a confirmed case (RR 2.9; 95%CI 1.6–4.5), who participated in extracurricular activities (RR 5.6; 95%CI 1.2–25.3), or whose caregiver is a healthcare worker who had contact with COVID-19 patients (RR 2.2; 95%CI 1.0–4.6) were at higher risk of seropositivity. If SARS-CoV2 circulation in the community is high, this will be reflected in the pediatric population with similar infection rates in children aged 6–12 years and 12–15 years. What is Known: •Children are generally less affected by COVID-19 than adults but SARS-CoV2 infection rates among children are not well known. •There were large regional differences in infection rates during the first wave of the SARS-CoV2 pandemic. What is New: •None of the primary schoolchildren (6–12 years) were seropositive for SARS-CoV2 in an area with a low community transmission, but infection rates were higher in adolescents (12–15 years). •In an area with high community transmission, seroprevalence rates in younger children were more comparable to those in adolescents.

Seroprevalence of SARS-CoV-2 Antibodies Among Children in School and Day Care in Montreal, Canada

“…For example, studies conducted in French 9 and British primary schools and French day cares 10 suggested little evidence of transmission from children to their peers or teachers, and a large Swiss cohort 11 found minimal clustering of seropositive cases within classes and schools, despite a clear increase in seroprevalence in children over a 5-month period of very high transmission. Determinants of SARS-CoV-2 seropositivity among children have included contact with a confirmed COVID-19 case, 10 , 12 health care workers in the household, 12 belonging to a minority racial or ethnic group, and geographical area. 11 One year into the pandemic, little is known regarding the seroprevalence of SARS-CoV-2 infection and its determinants among children and adolescents in Canada.…”

COVID-19 surveillance in the Flemish school system: development of systematic data collection within the Public Health School System and descriptive analysis of cases reported between October 2020 and June 2021

“…Even in the densely populated and well-connected region of Flanders, SARS-CoV-2 infection rates show a local distribution (34), dependent on heterogeneous mixing patterns and subject to different policies (35,36). Research shows that transmission in schools depends on the level of community transmission (37,38). School cases show a high correlation with the evolution of community cases in the general population in our study.…”

The COVID-19 pandemic in children and young people during 2020-2021: Learning about clinical presentation, patterns of spread, viral load, diagnosis and treatment

“…Studies conducted throughout 2021 brought further understanding to a spectrum of clinical symptoms and patterns of spread of the COVID-19 in children [ 47 - 70 ]. A study in Belgium found anti-SARS-CoV-2 antibodies in 4.4% of children in the low transmission region and 14.4% of children in the high transmission region.…”

“…A higher risk of seropositivity was associated with a contact with a confirmed case (RR = 2.9), participation in extracurricular activities (RR = 5.6), or a caregiver health care worker who had contact with COVID-19 patients (RR = 2.2). The study showed that, when SARS-CoV2 circulation in the community is high, this will be reflected in the pediatric population with similar infection rates [ 47 ]. A clear association was established between the duration of the COVID-19 symptoms in children and the generated IgG units [ 48 ].…”