Evolution of SARS-CoV-2 IgG Seroprevalence in Children and Factors Associated with Seroconversion: Results from a Multiple Time-Points Study in Friuli-Venezia Giulia Region, Italy

Abstract

Data on the effective burden of the SARS-CoV-2 pandemic in the pediatric population are limited. We aimed at assessing the prevalence of SARS-CoV-2 IgG antibodies in children at three subsequent time-points. The study was conducted between January 2021 and July 2021 among children referring to the Research Institute for Maternal and Child Health “Burlo Garofolo” in Trieste, a referral regional hospital in Friuli Venezia Giulia, Italy. A multivariate analysis was conducted to assess factors independently associated with seroconversion. A total of 594 children were included. Anti-SARS-CoV-2 trimeric Spike protein IgG antibodies were found in 32 (15.4%) children tested in April-May and in 20 (11.8%) in June–July 2021, compared with 24 (11.1%) of those tested in January–February 2021 (p = 0.37, Armitage exact test for trend over time p = 0.76). A subgroup analysis and a multivariate logistic regression analysis were performed considering sociodemographic, clinical, and historical variables. Three categories of children showed statistically significant increased odds of positive anti-SARS-CoV-2 IgG antibodies: children previously positive to a nasopharyngeal swab (AdjOR 15.41, 95%CI 3.44–69.04, p < 0.001), cohabitant with a person with an history of a previous positive nasopharyngeal swab (AdjOR 9.95, 95%CI 5.35–18.52, p < 0.001), and children with a foreign citizenship (AdjOR 2.4, 95%CI 1.05–5.70, p = 0.002). The study suggests that seroprevalence studies may be of limited help in estimating the prevalence of the COVID-19 pandemic in children. Further studies are needed to identify other markers of previous SARS-CoV-2 infection in children, such as CD4+ T cells or memory B-cells.

Seroprevalence of SARS-CoV-2 among Children Visiting a Tertiary Hospital during the Prevaccination Period, Southwest Region, Saudi Arabia

“…This result indicates that at least one in three unvaccinated children had acquired either symptomatic or asymptomatic COVID-19 infection within 18 months of the pandemic due to the presence of positive antibodies. The overall seroprevalence rate of SARS-CoV-2 among children in this study was higher than in other studies [13][14][15][16]19]. These previous studies showed a prevalence of 1.3% in Northern Cyprus [12], 5.8% among school-and preschool-age children in Canada [13], 9.5% to 15.4 (for IgG) in Italy [14,15], 27.1% in Saudi Arabia [19], and 25.3% in Brazil [16].…”

“…There have been some studies that examined the presence of antibodies among children. These previous studies reported different seroprevalence values, ranging from a low value of 1.3% in Northern Cyprus [12] to 5.8% among school-and preschool-age children in Canada [13], 9.5% and 15.4% (for IgG) in Italy [14,15], and a high of 25.3% in Brazil [16]. Further seroprevalence studies among children in diverse geographic locations can provide additional details on SARS-CoV-2 infection among children.…”

SARS-CoV-2 seroprevalence and determinants for salivary seropositivity among pupils and school staff: a prospective cohort study

“…Vulnerable pupils and those from lower SES schools were more at risk to test positive in our study. Similar findings were reported for schoolchildren belonging to racial and ethnic minorities in Canada [ 19 ], Italian children with foreign citizenship [ 24 ], and in low SES families in German schools [ 21 ]. Crowding and limited options to isolate were formulated as plausible causes, but neither we nor Zinszer et al observed an increased risk for seropositivity in larger families or in children who shared bedrooms.…”

National and regional prevalence of SARS-CoV-2 antibodies in primary and secondary school children in England: the School Infection Survey, a national open cohort study, November 2021SARS-CoV-2 antibody prevalence in school children

“…In England and elsewhere, opportunistic testing of residual sera from children having blood tests, in hospital, for example, has been used to assess SARS-CoV-2 antibody prevalence in children but these are prone to multiple biases, especially representativeness to the general population. 24 , 25 , 26 , 27 , 28 …”