SARS-CoV-2 seroepidemiology in paediatric population during Delta and Omicron predominance

Abstract

Limited prospective SARS-CoV-2 data in children regarding the impact of Omicron variant in seropositivity have been reported. We investigated SARS-CoV-2 seropositivity in children between 1 September 2021 and 30 April 2022, representing Delta and Omicron predominance periods. Serum samples from children admitted to the major tertiary Greek pediatric hospital for any cause, except for COVID-19, were randomly collected and tested for SARS-CoV-2 natural infection antibodies against nucleocapsid antigen (Elecsys® Anti-SARS-CoV-2 reagent). A total of 506/1312 (38.6%) seropositive children (0-16 years) were detected [males: 261/506(51.6%); median age (IQR): 95.2 months(24-144)]. Seropositivity rates (%) increased from Delta to Omicron period from 29.7% to 48.5% (P-value<0.0001). Seropositivity increased for all age groups, except for the age group of 0-1 year (P-value:0.914). The highest seropositivity rate was detected in April 2022 (52.6%) and reached 73.9% specifically for the age group 12-16 years. No significant differences were detected in seropositivity with respect to gender, origin, or hospitalization status. Median (IQR) antibody titers were higher in the Omicron vs Delta period in all age groups, especially in 12-16 years [32.2 COI (7-77.1) vs 11.4 COI(2.8-50.2), Pvalue:0.009]. During Omicron variant period increased SARS-CoV-2 seropositivity was detected in pediatric population, especially in adolescents, implicating either increased transmissibility or reinfection rates.

Seroprevalence of SARS-CoV-2 anti-nucleocapsid total Ig, anti-RBD IgG antibodies, and infection in Thailand: a cross-sectional survey from October 2022 to January 2023

“…2 . This is similar to the findings of other studies, which found that antibodies attributed to natural SARS-CoV-2 infection had a detectable high seropositive rate during the Omicron wave 23 , 33 – 35 . This positivity rate did not show any significant differences by sex or occupation.…”

SARS-CoV-2 BA.2 (Omicron) variant infection in pediatric liver transplanted recipients and cohabitants during 2022 Shanghai outbreak: a prospective cohort

“…In pediatric population, SARS-CoV-2 seropositivity increased during Omicron variant period compared with Delta waves, implicating either increased transmissibility or reinfection rates [43]. For children with native livers, the severance of the infection was usually milder and there was no significant difference in the risk of hospitalization for young children between Omicron and Delta Newly-onset LT complication None None None None None [44].…”

Immunology of Multisystem Inflammatory Syndrome after COVID-19 in Children: A Review of the Current Evidence

“…Pre-existing SARS-CoV-2 immunity, either as a result of natural infection or vaccination in children, seems to play a crucial role in MIS-C pathogenesis and severity. According to CDC, SARS-CoV-2 seroprevalence attributed only to infection-induced immunity has reached 92% in children by March 2023, while a significant increase in seropositivity during Omicron compared to Delta variant in the pediatric population has also been observed in Europe as well [ 20 ]. However, SARS-CoV-2 vaccination has also affected MIS-C incidence.…”