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Assessment of SARS-CoV-2 immunity in convalescent children and adolescents
  • +17
  • Patrick Ip,
  • Hing Wai Tsang,
  • Gilbert T Chua,
  • Kelvin KW,
  • Joshua Wong SC,
  • Tu WW,
  • Janette Kwok SY,
  • WHS Wong,
  • Xiwei Wang,
  • Yanmei Zhang,
  • Jaime Rosa Duque,
  • Godfrey Chan,
  • Chu WK,
  • Pang CP,
  • Paul Tam KH,
  • YL Lau,
  • Ian Wong,
  • Leung WH,
  • Kwok-Yung Yuen,
  • Mike Kwan YW
Patrick Ip
The University of Hong Kong Department of Paediatrics and Adolescent Medicine

Corresponding Author:patricip@hku.hk

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Hing Wai Tsang
The University of Hong Kong Department of Paediatrics and Adolescent Medicine
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Gilbert T Chua
The University of Hong Kong Department of Paediatrics and Adolescent Medicine
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Kelvin KW
State Key Laboratory for Emerging Infectious Diseases Carol Yu Centre for Infection Department of Microbiology Li Ka Shing Faculty of Medicine The University of Hong KongHong Kong SAR China
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Joshua Wong SC
Department of Paediatrics and Adolescent Medicine Prince Margaret Hospital Hospital Authority Hong Kong SAR China
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Tu WW
The University of Hong Kong Department of Paediatrics and Adolescent Medicine
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Janette Kwok SY
Department of Pathology Queen Mary Hospital Hospital Authority Hong Kong SAR China
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WHS Wong
The University of Hong Kong Department of Paediatrics and Adolescent Medicine
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Xiwei Wang
The University of Hong Kong Department of Paediatrics and Adolescent Medicine
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Yanmei Zhang
The University of Hong Kong Department of Paediatrics and Adolescent Medicine
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Jaime Rosa Duque
The University of Hong Kong Department of Paediatrics and Adolescent Medicine
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Godfrey Chan
The University of Hong Kong Department of Paediatrics and Adolescent Medicine
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Chu WK
The Chinese University of Hong Kong Department of Ophthalmology and Visual Sciences
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Pang CP
The Chinese University of Hong Kong Department of Ophthalmology and Visual Sciences
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Paul Tam KH
Department of Surgery and Dr Li Dak Sam Research Centre Li Ka Shing Faculty of Medicine The University of Hong Kong Hong Kong SAR China
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YL Lau
The University of Hong Kong Department of Paediatrics and Adolescent Medicine
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Ian Wong
The University of Hong Kong Department of Pharmacology and Pharmacy
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Leung WH
The University of Hong Kong Department of Paediatrics and Adolescent Medicine
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Kwok-Yung Yuen
State Key Laboratory for Emerging Infectious Diseases Carol Yu Centre for Infection Department of Microbiology Li Ka Shing Faculty of Medicine The University of Hong KongHong Kong SAR China
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Mike Kwan YW
Department of Paediatrics and Adolescent Medicine Prince Margaret Hospital Hospital Authority Hong Kong SAR China
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Abstract

Background: Persistence of protective immunity for SARS-CoV-2 is important against reinfection. Knowledge on SARS-CoV-2 immunity in pediatric patients is currently lacking. We opted to assess the SARS-CoV-2 adaptive immunity in recovered children and adolescents, addressing the pediatrics specific immunity towards COVID-19. Method: Two independent assays were performed to investigate humoral and cellular immunological memory in pediatric convalescent COVID-19 patients. Specifically, RBD IgG, CD4+, and CD8+ T cell responses were identified and quantified in recovered children and adolescents. Results: SARS-CoV-2-specific RBD IgG detected in recovered patients had a half-life of 121.6 days and estimated duration of 7.9 months compared with baseline levels in controls. The specific T cell response was shown to be independent of recovery time. Both CD4+ and CD8+ T cells showed robust responses not only to spike (S) peptides (a main target of vaccine platforms) but were also similarly activated when stimulated by membrane (M) and nuclear (N) peptides. Importantly, we found the differences in the adaptive responses were correlated with the age of the recovered patients. The CD4+ T cell response to SARS-CoV-2 S peptide in children aged <12 years correlated with higher SARS-CoV-2 RBD IgG levels, whereas higher level of CD8+ T cells in children aged ≥12 years, suggesting the importance of a T cell-dependent humoral response in younger children under 12 years. Conclusion: Both cellular and humoral immunity against SARS-CoV-2 infections can be induced in pediatric patients. Our important findings provide fundamental knowledge on the immune memory responses to SARS-CoV-2 in recovered pediatric patients.