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Haile SR, Raineri A, Rueegg S, Radtke T, Ulyte A, Puhan MA, Kriemler S. Heterogeneous evolution of SARS-CoV-2 seroprevalence in school-age children: Results from the school-based cohort study Ciao Corona in November-December 2021 in the canton of Zurich. Swiss Med Wkly 2023; 153:40035. [PMID: 36787493 DOI: 10.57187/smw.2023.40035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
BACKGROUND Much remains unknown regarding the evolution of SARS-CoV-2 seroprevalence and variability in seropositive children in districts, schools and classes as only a few school-based cohort studies exist. Vaccination of children, initiated at different times for different age groups, adds additional complexity to the understanding of how seroprevalence developed in the school aged population. AIM We investigated the evolution of SARS-CoV-2 seroprevalence in children and its variability in districts, schools and classes in Switzerland from June/July 2020 to November/December 2021. METHODS In this school-based cohort study, SARS-CoV-2 antibodies were measured in primary and secondary school children from randomly selected schools in the canton of Zurich in October/November 2020, March/April 2021 and November/December 2021. Seroprevalence was estimated using Bayesian logistic regression to adjust for test sensitivity and specificity. Variability of seroprevalence between school classes was expressed as maximum minus minimum seroprevalence in a class and summarised as median (interquartile range). RESULTS 1875 children from 287 classes in 43 schools were tested, with median age 12 years (range 6-17), 51% 12+ vaccinated. Seroprevalence increased from 5.6% (95% credible interval [CrI] 3.5-7.6%) to 31.1% (95% CrI 27.0-36.1%) in unvaccinated children, and 46.4% (95% CrI 42.6-50.9%) in all children (including vaccinated). Earlier in the pandemic, seropositivity rates in primary schools were similar to or slightly higher (<5%) than those in secondary schools, but by late 2021, primary schools had 12.3% (44.3%) lower seroprevalence for unvaccinated (all) subjects. Variability in seroprevalence among districts and schools increased more than two-fold over time, and in classes from 11% (95% CrI 7-17%) to 40% (95% CrI 22-49%). CONCLUSIONS Seroprevalence in children increased greatly, especially in 2021 following introduction of vaccines. Variability in seroprevalence was high and increased substantially over time, suggesting complex transmission chains.
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Affiliation(s)
- Sarah R Haile
- Epidemiology, Biostatistics and Prevention Institute (EBPI), University of Zurich, Zurich, Switzerland
| | - Alessia Raineri
- Epidemiology, Biostatistics and Prevention Institute (EBPI), University of Zurich, Zurich, Switzerland
| | - Sonja Rueegg
- Epidemiology, Biostatistics and Prevention Institute (EBPI), University of Zurich, Zurich, Switzerland
| | - Thomas Radtke
- Epidemiology, Biostatistics and Prevention Institute (EBPI), University of Zurich, Zurich, Switzerland
| | - Agne Ulyte
- Epidemiology, Biostatistics and Prevention Institute (EBPI), University of Zurich, Zurich, Switzerland
| | - Milo A Puhan
- Epidemiology, Biostatistics and Prevention Institute (EBPI), University of Zurich, Zurich, Switzerland
| | - Susi Kriemler
- Epidemiology, Biostatistics and Prevention Institute (EBPI), University of Zurich, Zurich, Switzerland
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Tunheim G, Rø GØI, Chopra A, Aase A, Kran AB, Vaage JT, Lund‐Johansen F, Hungnes O. Prevalence of antibodies against SARS-CoV-2 in the Norwegian population, August 2021. Influenza Other Respir Viruses 2022; 16:1004-1013. [PMID: 35770841 PMCID: PMC9349429 DOI: 10.1111/irv.13024] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Revised: 06/17/2022] [Accepted: 06/18/2022] [Indexed: 11/28/2022] Open
Abstract
BACKGROUND One year into the COVID-19 pandemic, the cumulative number of confirmed COVID-19 cases in Norway was still low. In January 2021, when the Norwegian COVID-19 vaccination campaign started, the national seroprevalence estimate of SARS-CoV-2 antibodies was 3.2%. We have conducted a nationwide cross-sectional study in August 2021 to investigate the overall prevalence of SARS-CoV-2 antibodies in Norway after 8 months of COVID-19 mass vaccination and a third wave of SARS-CoV-2 infection. METHODS Residual sera were collected from laboratories across Norway in August 2021. In IgG antibodies against the spike protein, the spike receptor binding domain (RBD) and the nucleocapsid protein of SARS-CoV-2 were measured by a bead-based flow cytometric assay. RESULTS In total, 1926 residual sera were collected from individuals aged 0-98 years; 55.1% were from women. The overall national estimated seroprevalence from vaccination and/or infection was 62.6% (credible interval [CrI] 60.1%-65.2%) based on having antibodies against both spike and RBD. Estimated seroprevalence increased with age. Among all samples, 11.7% had antibodies against nucleocapsid. For unvaccinated children <12 years, the seroprevalence estimate due to SARS-CoV-2 infection was 12.5% (95% CrI 9.3%-16.1%). Of seropositive samples from the unvaccinated children, 31.9% lacked anti-nucleocapsid antibodies. CONCLUSIONS The high overall SARS-CoV-2 seroprevalence estimates are in line with Norwegian registry data. Vaccination, not infection, contributed the most to the high seroprevalence in August 2021. Lack of antibodies against nucleocapsid should not automatically be interpreted as absence of previous infection as this could lead to underestimation of COVID-19 cases in seroprevalence studies.
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Affiliation(s)
- Gro Tunheim
- Division of Infection ControlNorwegian Institute of Public Health (NIPH)OsloNorway
| | | | - Adity Chopra
- Department of ImmunologyOslo University HospitalOsloNorway
| | - Audun Aase
- Division of Infection ControlNorwegian Institute of Public Health (NIPH)OsloNorway
| | | | - John Torgils Vaage
- Department of ImmunologyOslo University HospitalOsloNorway
- Institute of Clinical MedicineUniversity of OsloOsloNorway
| | | | - Olav Hungnes
- Division of Infection ControlNorwegian Institute of Public Health (NIPH)OsloNorway
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Sieber J, Mayer M, Schmidthaler K, Kopanja S, Camp JV, Popovitsch A, Dwivedi V, Hoz J, Schoof A, Weseslindtner L, Szépfalusi Z, Stiasny K, Aberle JH. Long-Lived Immunity in SARS-CoV-2-Recovered Children and Its Neutralizing Capacity Against Omicron. Front Immunol 2022; 13:882456. [PMID: 35663948 PMCID: PMC9157051 DOI: 10.3389/fimmu.2022.882456] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Accepted: 04/19/2022] [Indexed: 12/26/2022] Open
Abstract
SARS-CoV-2 infection is effectively controlled by humoral and cellular immune responses. However, the durability of immunity in children as well as the ability to neutralize variants of concern are unclear. Here, we assessed T cell and antibody responses in a longitudinal cohort of children after asymptomatic or mild COVID-19 over a 12-month period. Antigen-specific CD4 T cells remained stable over time, while CD8 T cells declined. SARS-CoV-2 infection induced long-lived neutralizing antibodies against ancestral SARS-CoV-2 (D614G isolate), but with poor cross-neutralization of omicron. Importantly, recall responses to vaccination in children with pre-existing immunity yielded neutralizing antibody activities against D614G and omicron BA.1 and BA.2 variants that were 3.9-fold, 9.9-fold and 14-fold higher than primary vaccine responses in seronegative children. Together, our findings demonstrate that SARS-CoV-2 infection in children induces robust memory T cells and antibodies that persist for more than 12 months, but lack neutralizing activity against omicron. Vaccination of pre-immune children, however, substantially improves the omicron-neutralizing capacity.
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Affiliation(s)
- Justyna Sieber
- Division of Pediatric Pulmonology, Allergy and Endocrinology, Department of Pediatrics and Adolescent Medicine, Comprehensive Center of Pediatrics, Medical University of Vienna, Vienna, Austria
- Department of Clinical Immunology, Wroclaw Medical University, Wroclaw, Poland
| | - Margareta Mayer
- Center for Virology, Medical University of Vienna, Vienna, Austria
| | - Klara Schmidthaler
- Division of Pediatric Pulmonology, Allergy and Endocrinology, Department of Pediatrics and Adolescent Medicine, Comprehensive Center of Pediatrics, Medical University of Vienna, Vienna, Austria
| | - Sonja Kopanja
- Division of Pediatric Pulmonology, Allergy and Endocrinology, Department of Pediatrics and Adolescent Medicine, Comprehensive Center of Pediatrics, Medical University of Vienna, Vienna, Austria
| | - Jeremy V. Camp
- Center for Virology, Medical University of Vienna, Vienna, Austria
| | | | - Varsha Dwivedi
- Division of Pediatric Pulmonology, Allergy and Endocrinology, Department of Pediatrics and Adolescent Medicine, Comprehensive Center of Pediatrics, Medical University of Vienna, Vienna, Austria
| | - Jakub Hoz
- Division of Pediatric Pulmonology, Allergy and Endocrinology, Department of Pediatrics and Adolescent Medicine, Comprehensive Center of Pediatrics, Medical University of Vienna, Vienna, Austria
| | - Anja Schoof
- Division of Pediatric Pulmonology, Allergy and Endocrinology, Department of Pediatrics and Adolescent Medicine, Comprehensive Center of Pediatrics, Medical University of Vienna, Vienna, Austria
| | | | - Zsolt Szépfalusi
- Division of Pediatric Pulmonology, Allergy and Endocrinology, Department of Pediatrics and Adolescent Medicine, Comprehensive Center of Pediatrics, Medical University of Vienna, Vienna, Austria
| | - Karin Stiasny
- Center for Virology, Medical University of Vienna, Vienna, Austria
| | - Judith H. Aberle
- Center for Virology, Medical University of Vienna, Vienna, Austria
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