Immunogenicity Against SARS-CoV-2 in COVID-19 Close Contacts

Study Overview
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Brief Summary
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This study will investigate the presence of SARS-CoV-2 neutralizing antibody and its association with demographic information, medical history of SARS-CoV-2 infected individuals, exposure history of close contacts, vaccination status, and compliance with the strategies for self-quarantine to prevent the transmission in the community where SARS-CoV-2 infected individuals were home-quarantined and treated.

Detailed Description
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In the 4th outbreak of the covid-19 pandemic in Ho Chi Minh City since 27 April 2021, asymptomatic or mild covid-19 patients were self-quarantined and treated at home. This home care setting could yield risk of SARS-CoV-2 transmission from the index cases to the people living surroundings. Therefore, this study will be performed to investigate the immunogenicity against SARS-CoV-2 in household members or people lived in the same municipality with home-quarantined covid-19 patients. All people over 18 years old, living in 2 blocks (V and Y) of Ngo Gia Tu apartment, which is located in District 10, Ho Chi Minh City, will be recruited into this study. A survey will be conducted using a questionnaire to collect the data related to the basic demographic information, medical history of SARS-CoV-2 infected individuals, exposure history of close contacts, vaccination status, and compliance with the strategies for self-quarantine to prevent the transmission in the community. At the time of recruitment, Covid-19 rapid antigen detection tests using nasopharyngeal swabs will be performed for all study subjects. In addition, a total of 5mL of intravenous blood samples will be collected for serum extraction and DNA isolation. SARS-CoV-2 neutralizing antibody levels in serum samples will be evaluated by a surrogate virus neutralization test by using NeutraLISA kit® (Euroimmun, Luebeck, Germany). DNA will be isolated and stored for further use in investigating the association of ACE2 genetic polymorphisms with the prevalence of SARS-CoV-2 neutralizing antibodies.

Official Title
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Characteristics of Immunogenicity Against SARS-CoV-2 in the Community With Home-quarantined Covid-19 Patients in Ho Chi Minh City, Vietnam

Conditions
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Covid19, Vaccine Reaction

Intervention / Treatment
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* Diagnostic Test: SARS-CoV-2 IgG II Quant


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: People who lived in the two blocks (V and Y) of Ngo Gia Tu apartment, located in District 10, Ho Chi Minh City, Vietnam, from July to September 2021 18 years of age and older Ability to understand and willingness to sign a written informed consent document. Exclusion Criteria: People who were diagnosed with primary or secondary immunodeficiencies induced by diseases or medical treatments (immunosuppressants, chemotherapy, radiation therapy, ect.)

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Study Plan
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How is the study designed?
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Arms and Interventions

| Intervention/Treatment |
| --- |
|Diagnostic Test: SARS-CoV-2 IgG II Quant|3ml of blood samples are collected, contained in heparin-free tubes, and centrifuged. Blood serum samples are collected and stored at the -80 Celcius degree. SARS-CoV-2 IgG antibodies in human serum and plasma are detected using chemiluminescent microparticle immunoassay (CMIA) technology on the ARCHITECT I 1000r System. Quality Control procedures will take place once daily, with three levels: one negative control and two positive controls. Sample, SARS-CoV-2 antigen-coated paramagnetic microparticles, and assay diluent are combined and incubated. The SARS-CoV-2 IgG antibodies present in the sample bind to the antigen-coated microparticles. The resulting chemiluminescent reaction is measured as a relative light unit (RLU). There is a direct relationship between the titres of IgG antibodies to SARS-CoV-2 in the sample and the RLU detected by the system optics. Interpretation of Results: < 50.0 AU/mL, Negative, ≥ 50.0 AU/mL, Positive|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| SARS-CoV-2 anti-RBD IgG concentration | SARS-CoV-2 anti-RBD IgG antibody concentration was reported after analysing the specimen | Up to 1 week after examination |