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.

Marzia Lazzerini,Ilaria Mariani,Manola Comar,Giovanni Rezza,Giada Vittori,Egidio Barbi,Pasqualina Leone,Simone Benvenuto,Silvana Schreiber,Paola Stefanelli,Alberto Tommasini,Giorgio Fedele

doi:10.3390/children9020246

Marzia Lazzerini, Ilaria Mariani + Show 10 more

Open Access

https://doi.org/10.3390/children9020246

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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.

Highlights

IntroductionCOVID-19 has been a major public health concern worldwide since 2020, and major efforts, with a high cost for the health system and the entire society, have been made to mitigate its spread
IgG antibodies across three time periods: the second wave of COVID-19 epidemic in the region versus the end of the third wave and the following summertime, when a low incidence of cases was reported
When compared to the COVID-19 epidemic curve in Friuli Venezia Giulia Region (FVG) Region, IgG antibodies rates had a spike after the epidemic peaks, but decreased rapidly

Summary

Introduction

COVID-19 has been a major public health concern worldwide since 2020, and major efforts, with a high cost for the health system and the entire society, have been made to mitigate its spread. Updated data on COVID-19 incidence and prevalence, as well as studies on the immunological response to SARS-CoV-2 in different populations, are critical to plan effective prevention and control efforts and reduce cost for the society [1,2]. Longitudinal surveys to continually monitor SARS-CoV2 seroprevalence rates in different age subgroups have been considered important to support prevention and control efforts [1,2]. In children, the lack of an accurate diagnostic tests acceptable to the wide public, as well as the high rate of asymptomatic or oligosymptomatic cases, limit the availability of reliable information on COVID-19 incidence [2,3]. A better understanding of children’s susceptibility to SARSCoV-2 infection may allow to better plan public health interventions, such as school closure

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