Study Results
The study team has not published outcome measurements, participant flow, or safety data for this trial yet. Check back later for updates.
Basic Information
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COMPLETED
9600 participants
OBSERVATIONAL
2022-04-28
2023-03-31
Brief Summary
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Detailed Description
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The investigators recruited healthy blood donors by convenience sampling at the five largest blood donation centres (Mongkok, Causeway, Kwun Tong, Tsuen Wan and Shatin) of the Hong Kong Red Cross Blood Transfusion Service (HKRCBTS). Blood donors were matched by the HKRCBTS and the Hong Kong Department of Health with official vaccination records via unique Blood Transfusion Service donor identification numbers. The records were then anonymised and provided to the study team. Blood donors were also provided with the option of self-reporting their vaccination and COVID-19 infection history.
Since the investigators need to distinguish past infection from vaccine induced immunity, they used serological test strategies that would differentiate natural infection from vaccine immunity. The investigators have previously shown that IgG antibody to the Nucleocapsid protein of SARS-CoV-2 (whole protein and the C-terminal domain) provides evidence of past infection and is not elicited by BNT162b2 vaccine but may be elicited by CoronaVac vaccine (Wu et al. 2021, Mok et al. 2021) . They have also shown IgG antibody to ORF8 is elicited by past infection and not by either CoronaVac or BNT162b2 (Hachim et al. 2020). The investigators used these assays to assess evidence of natural infection in blood donor samples.
Through the above procedures, the investigators obtained detailed serial cross-sectional (weekly between mid-April and the end of July, followed by monthly until the end of 2022) estimates of the age-specific distribution of SARS-CoV-2 Omicron variant-specific antibody positivity levels. The investigators derived age-specific infection attack rates and age-specific population immunity levels and tracked the magnitude of individual-level and population-level waning immunity over time.
Conditions
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Study Design
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ECOLOGIC_OR_COMMUNITY
CROSS_SECTIONAL
Study Groups
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Unvaccinated blood donors
Blood donors who were unvaccinated with any COVID-19 vaccine by study recruitment
No interventions assigned to this group
Blood donors vaccinated with BNT162b2
Blood donors who were vaccinated with one or more doses of the mRNA vaccine Comirnaty (BNT162b2 mRNA, BioNTech/Fosun-Pharma, Mainz, Germany/Shanghai, China) by study recruitment.
mRNA BNT162b2 vaccine
mRNA vaccine Comirnaty (BNT162b2 mRNA, BioNTech/Fosun-Pharma, Mainz, Germany/Shanghai, China)
Blood donors vaccinated with CoronaVac
Blood donors who were vaccinated with one or more doses of the inactivated CoronaVac (Sinovac life Sciences, Beijing, China) vaccine by study recruitment.
CoronaVac vaccine
Inactivated CoronaVac vaccine (Sinovac Life Sciences, Beijing, China)
Interventions
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mRNA BNT162b2 vaccine
mRNA vaccine Comirnaty (BNT162b2 mRNA, BioNTech/Fosun-Pharma, Mainz, Germany/Shanghai, China)
CoronaVac vaccine
Inactivated CoronaVac vaccine (Sinovac Life Sciences, Beijing, China)
Eligibility Criteria
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Inclusion Criteria
* Weigh 41 kg or above (90 lbs or above)
* Aged between 18 and 65
Exclusion Criteria
18 Years
65 Years
ALL
Yes
Sponsors
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The University of Hong Kong
OTHER
Responsible Party
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Principal Investigators
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Joseph T Wu
Role: PRINCIPAL_INVESTIGATOR
The University of Hong Kong
Locations
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The University of Hong Kong
Hong Kong, , Hong Kong
Countries
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Other Identifiers
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UW 20-132
Identifier Type: -
Identifier Source: org_study_id