COVID-19NCT05271669
COVID-19 Immunity and Changes Over Time
An observational study of COVID-19, run by Chinese University of Hong Kong at 1 site in China.
Trial summary
The risk of household spread of SARS-CoV-2 hinges on both the transmission dynamics of the virus circulating in the community as well as the seroprotection pattern of constituent members, which can be attributed to vaccination and previous infections. Read more about this study
- Who is it for?
- Any age
- Conditions the study is for
- COVID-19
- How many people
- 1,350 participants
- Where
- 1 siteChina
- Study dates
- 6 Jun 2022to 31 Jan 2027
- Phase
- Observational
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages Any age
- All sexes
- Child, Adult, Older adult
Study population: Adults of households enrolling in a population cohort covering residents from all 18 districts in Hong Kong.
Who may be able to join
- adults of age 18 or above, or children under the age of 18 with informed consent of the legal guardian
- normally residing in Hong Kong
- could communicate in spoken and written Chinese and/or English
Who cannot join
- individuals with mental illness
- prisoners
Trial locations and contacts
1 site in 1 country.
About this study
Official title: Patterns of SARS-CoV-2 Immunity at Household Level and Their Changes Over Time
The risk of household spread of SARS-CoV-2 hinges on both the transmission dynamics of the virus circulating in the community as well as the seroprotection pattern of constituent members, which can be attributed to vaccination and previous infections. This study is conceptualised to assess the dynamicity of SARS-CoV-2 risk at the household level, through monitoring the pattern of seroprotection, in conjunction with the vaccination coverage, history of infection and exposure risk in the setting of Hong Kong.
Read the detailed description
The aim of this study is to assess the SARS-CoV-2 risk at the household level, with the objectives of (a) determining the coverage of vaccination and its changes over time; (b) monitoring pattern of exposure and history of infection; and (c) evaluating the level of seroprotection and its longitudinal trend.
A cohort of households comprising 900 persons would be recruited. Invited participants would be attend the Research Centre for blood sampling and the completion of a simple questionnaire at 3 different timepoints at 12-18 months apart. A questionnaire would be administered to capture the following characteristics: (a) Socio-demographics; (b) History of SARS-CoV-2 infection; (c) adoption of precautionary measures; (d) SARS-CoV-2 testing history and (e) SARS-CoV-2 vaccination uptake.
Participants would be tested for SARS-CoV-2 serology. The main markers for measurement are nucleocapsid antibody for inferring past infection, spike antibody for the immunological responses, and seroprotection by SARS-CoV-2 surrogate virus neutralisation test.
- Conditions
- COVID-19
- Keywords
- serology, cohort study, SARS-CoV-2 antibody
- Medical subject headings
- COVID-19
What is being measured
The primary outcome is the main question the study is designed to answer.
Proportion of participants with COVID-19 protective immunity
Prevalence of SARS-CoV-2 spike antibody
Measured: 1 year
Proportion of participants with marker of past COVID-19 infection
Prevalence of SARS-CoV-2 nucleocapsid antibody
Measured: 1 year
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted9 Mar 2022
- Study start6 Jun 2022
- Primary completion31 Jul 2026
- Study completion31 Jan 2027 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for COVID-19Studies of the same condition, open and under way.
- More trials run by Chinese University of Hong KongThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Observational
- Observational model
- Cohort
- Time perspective
- Prospective
- Enrolment
- 1,350 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Chinese University of Hong Kong
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Shui-Shan Lee, MD, Chinese University of Hong Kong
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05271669
- Sponsor's protocol ID
- Protocol HK COVID cohort 2021
- Status last verified
- Oct 2026
- First submitted
- 7 Mar 2022
- Last updated
- 22 Oct 2026
- Results posted
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
Study at a glance
From the registry record, last updated by the sponsor on 22 Oct 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Patterns of SARS-CoV-2 Immunity at Household Level and Their Changes Over Time
- ClinicalTrials.gov ID
- NCT05271669
- Acronym / sponsor ID
- Protocol HK COVID cohort 2021
- Conditions
- COVID-19
- Keywords
- serology, cohort study, SARS-CoV-2 antibody
- Study type
- Observational
- Recruitment status
- Active, not recruiting
- Enrolment
- 1,350 participants (estimated)
- Lead sponsor
- Chinese University of Hong KongUniversity, hospital or other
- Study start
- 6 Jun 2022 (actual)
- Primary completion
- 31 Jul 2026 (actual)
- Study completion
- 31 Jan 2027 (estimated)
- First posted
- 9 Mar 2022 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The risk of household spread of SARS-CoV-2 hinges on both the transmission dynamics of the virus circulating in the community as well as the seroprotection pattern of constituent members, which can be attributed to vaccination and previous infections. This study is conceptualised to assess the dynamicity of SARS-CoV-2 risk at the household level, through monitoring the pattern of seroprotection, in conjunction with the vaccination coverage, history of infection and exposure risk in the setting of Hong Kong.
Detailed description
The aim of this study is to assess the SARS-CoV-2 risk at the household level, with the objectives of (a) determining the coverage of vaccination and its changes over time; (b) monitoring pattern of exposure and history of infection; and (c) evaluating the level of seroprotection and its longitudinal trend.
A cohort of households comprising 900 persons would be recruited. Invited participants would be attend the Research Centre for blood sampling and the completion of a simple questionnaire at 3 different timepoints at 12-18 months apart. A questionnaire would be administered to capture the following characteristics: (a) Socio-demographics; (b) History of SARS-CoV-2 infection; (c) adoption of precautionary measures; (d) SARS-CoV-2 testing history and (e) SARS-CoV-2 vaccination uptake.
Participants would be tested for SARS-CoV-2 serology. The main markers for measurement are nucleocapsid antibody for inferring past infection, spike antibody for the immunological responses, and seroprotection by SARS-CoV-2 surrogate virus neutralisation test.
Study design
- Observational model
- Cohort
- Time perspective
- Prospective
Who may qualify
- Sex
- All
- Age groups
- Child, Adult, Older adult
- Study population
- Adults of households enrolling in a population cohort covering residents from all 18 districts in Hong Kong.
Key inclusion criteria (3 listed)
- adults of age 18 or above, or children under the age of 18 with informed consent of the legal guardian
- normally residing in Hong Kong
- could communicate in spoken and written Chinese and/or English
Key exclusion criteria (2 listed)
- individuals with mental illness
- prisoners
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Primary outcome
Proportion of participants with COVID-19 protective immunity
Time frame: 1 year
Prevalence of SARS-CoV-2 spike antibody
Proportion of participants with marker of past COVID-19 infection
Time frame: 1 year
Prevalence of SARS-CoV-2 nucleocapsid antibody
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 22 Oct 2026.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
The record lists no contact. Use the official record to reach the sponsor.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of COVID-19, run by Chinese University of Hong Kong at 1 site in China.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 3 inclusion and 2 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: under way, not looking for participants, as of the sponsor's last update on 22 Oct 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in China. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Proportion of participants with COVID-19 protective immunity (time frame: 1 year). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 22 Oct 2026.