Seroprevalence of Infection-induced SARS-CoV-2 Antibodies (COVID-19) in Children


It is unknown what proportion of children have been exposed to SARS-CoV-2 and how many have antibodies among children seeking medical care for non-Covid-19 related conditions. The aim of this study is to identify children with IgG antibodies to SARS-CoV-2 who have not been previously diagnosed and are presumed/confirmed Covid-19 negative, then determine the level of immunity in this population which could inform further decisions about covid-19 vaccine strategies for children

Full Title of Study: “Seroprevalence of Infection-induced IgG Antibodies to SARS-CoV-2 in Children Seeking Medical Care in Vietnam”

Study Type

  • Study Type: Observational
  • Study Design
    • Time Perspective: Cross-Sectional
  • Study Primary Completion Date: June 5, 2022

Detailed Description

Enrolled participants will have a survey about demographic information, history of previous suspected/confirmed Covid-19 infection or exposed to SARS-CoV-2, Covid-19 vaccination status. For participants aged less than 12 months, participants' mothers' status of Covid-19 vaccination and/or previous infection will be recorded. Participants will then complete serologic testing for SARS-CoV-2 IgG antibodies using residual plasma specimens collected/stored for routine laboratory tests on the date of enrollment. The study will characterize the prevalence of antibody positivity in this population and assess whether there is a correlation between demographic characteristics and antibodies levels.


  • Diagnostic Test: SARS-CoV-2 IgG Antibody testing
    • IgG Antibody testing for previous exposure to SARS-CoV-2

Clinical Trial Outcome Measures

Primary Measures

  • The percentage of children with IgG SARS-CoV-2 antibodies in Plasma
    • Time Frame: 6 month
    • The percentage of children with IgG SARS-CoV-2 antibodies to the total number of children enrolled in the study
  • Immunoglobulins (G) to SARS-CoV-2 in plasma
    • Time Frame: 6 month
    • Mean antibody titres (IgG) to SARS-CoV-2 in plasma using SIEMENS assays

Secondary Measures

  • Measure of association between SARS-CoV-2 IgG seropositivity and characteristics
    • Time Frame: 6 month
    • socio-demographics, previous exposure to SARS-CoV-2

Participating in This Clinical Trial

Inclusion Criteria

  • Age ≤ 18 years old. – Seeking medical care at Vietnam National Children's Hospital for any condition not related to acute Covid-19 – Have not been previously diagnosed and are presumed/confirmed COVID-19 negative – Have blood specimens collected for any routine biochemistry test on the date enrollment Exclusion Criteria:

  • Refusal to participate in this study.

Gender Eligibility: All

Minimum Age: 0 Years

Maximum Age: 18 Years

Are Healthy Volunteers Accepted: No

Investigator Details

  • Lead Sponsor
    • National Children’s Hospital, Vietnam
  • Provider of Information About this Clinical Study
    • Principal Investigator: Phuc Huu Phan, Physician – National Children’s Hospital, Vietnam
  • Overall Official(s)
    • Phuc H Phan, MD, Principal Investigator, Vietnam National Children’s Hospital
  • Overall Contact(s)
    • Phuc H Phan, MD, 84912880105,

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