SARS-CoV-2NCT04939402
SARS-COV-2 Seroprevalence and Seroconversion Among Employees of the UZ Brussel Following COVID-19 Vaccination Using an Adenoviral Vector
A study testing Serological testing in people with SARS-CoV-2 and Covid19, run by Universitair Ziekenhuis Brussel at 1 site in Belgium.
Trial summary
A novel zoonotic coronavirus was discovered in Wuhan (Hubei Province, China) mid-December 2019 and was named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The virus rapidly spread to the rest of the world, including Europe and explicitly affects the respiratory system, generating Coronavirus disease… Read more about this study
- Who is it for?
- Ages 18 years and olderHealthy volunteers can take part
- Conditions the study is for
- SARS-CoV-2, Covid19
- What is being tested?
- Serological testing
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 200 participants
- Where
- 1 siteBelgium
- Study dates
- 5 May 2021to Jun 2028
- Phase
- Interventional
- 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 18 years and older
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Who may be able to join
- Any adult employee of the UZ Brussel at T1 who has been vaccinated at the UZ Brussel with ChAdOx1 nCoV-19 vaccine between the 2nd of March and the 9th of March 2021 after participating to phase 4 of the COVEMUZ study between the 25th of January and the 12th of February and has provided a signed informed consent.
Who cannot join
- UZ Brussel employees not active during the inclusion period (T1).
Trial locations and contacts
1 site in 1 country.
About this study
Official title: SARS-COV-2 Seroprevalence and Seroconversion Among Employees of the Universitair Ziekenhuis Brussel Following COVID-19 Vaccination Using an Adenoviral Vector
A novel zoonotic coronavirus was discovered in Wuhan (Hubei Province, China) mid-December 2019 and was named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The virus rapidly spread to the rest of the world, including Europe and explicitly affects the respiratory system, generating Coronavirus disease 2019 (COVID-19).
Employees of the university hospital of Brussels (UZ Brussel) presenting symptoms suggestive of COVID-19 are offered to be tested with real-time PCR on nasopharyngeal swabs. As asymptomatic infections have been described and as the PCR can be negative when taken late after onset of symptoms, serologic tests can be performed. The SARS-CoV 2003 epidemic demonstrated that serological assays were a useful diagnostic tool of non-acute infections. Although it is still uncertain whether convalescing patients have a risk of re-infection, recent data suggest that SARS-CoV-2 antibodies could protect at least for some time from subsequent viral exposures.
Read more
As the COVID-19 pandemic had devastating medical, economic and social consequences, safe and effective prophylactic vaccines were urgently needed. And thus several candidate vaccines against SARS-CoV-2 have been developed. The vaccination campaign of the health care workers of the UZ Brussel started mid January 2021. The first available vaccine was the BNT162b2 (Pfizer) vaccine. Early March 2021, in order to accelerate the vaccination of the UZ Brussel employees, the ChAdOx1 nCoV-19 (AZD12222) (Oxford, AstaZeneca) vaccination program was implemented in parallel with the BNT162b2 vaccination program In the COVEMUZ-2 study the investigators have already started to document the SARS-CoV-2 seroprevalence and seroconversion among vaccinated employees (using BNT162b2) in the UZ Brussels.
In this study, the investigators aim to prospectively document the SARS-CoV-2 seroprevalence and seroconversion among vaccinated employees (using ChAdOx1 nCoV-19) of the UZ Brussel, at three different time points, namely 6 weeks (+/- 2 weeks; T1), 6 months (+/- 1 month; T2) and 12 months (+/- 1 month; T3) after the second vaccination.
Read the detailed description
A novel zoonotic coronavirus was discovered in Wuhan (Hubei Province, China) mid-December 2019 and was named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The virus rapidly spread to the rest of the world, including Europe and explicitly affects the respiratory system, generating Coronavirus disease 2019 (COVID-19).
Employees of the university hospital of Brussels (UZ Brussel) presenting symptoms suggestive of COVID-19 are offered to be tested with real-time PCR on nasopharyngeal swabs. As asymptomatic infections have been described and as the PCR can be negative when taken late after onset of symptoms, serologic tests can be performed. The SARS-CoV 2003 epidemic demonstrated that serological assays were a useful diagnostic tool of non-acute infections. Although it is still uncertain whether convalescing patients have a risk of re-infection, recent data suggest that SARS-CoV-2 antibodies could protect at least for some time from subsequent viral exposures.
As the COVID-19 pandemic had devastating medical, economic and social consequences, safe and effective prophylactic vaccines were urgently needed. And thus several candidate vaccines against SARS-CoV-2 have been developed. The vaccination campaign of the health care workers of the UZ Brussel started mid January 2021. The first available vaccine was the BNT162b2 (Pfizer) vaccine. Early March 2021, in order to accelerate the vaccination of the UZ Brussel employees, the ChAdOx1 nCoV-19 (AZD12222) (Oxford, AstaZeneca) vaccination program was implemented in parallel with the BNT162b2 vaccination program In the COVEMUZ-2 study the investigators have already started to document the SARS-CoV-2 seroprevalence and seroconversion among vaccinated employees (using BNT162b2) in the UZ Brussels.
In this study, the investigators aim to prospectively document the SARS-CoV-2 seroprevalence and seroconversion among vaccinated employees (using ChAdOx1 nCoV-19) of the UZ Brussel, at three different time points, namely 6 weeks (+/- 2 weeks; T1), 6 months (+/- 1 month; T2) and 12 months (+/- 1 month; T3) after the second vaccination.
- Conditions
- SARS-CoV-2, Covid19
- Being tested
- Serological testing
- Medical subject headings
- COVID-19
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Serological testingDiagnostic test
Antibody testing for Sars-CoV-2 specific antibodies in blood + T cell immunity
| Study group | Role | What they receive |
|---|---|---|
| General | Other | All patients follow this arm. Patients will undergo 3 blood sample testings at 3 different time points and have to fill in a questionnaire at 3 different time points Receives: Diagnostic Test: Serological testing |
What is being measured
The primary outcome is the main question the study is designed to answer.
Seroprevalence
To document SARS-CoV-2 seroprevalence among employees of the UZ Brussel after ChAdOx1 nCoV-19 vaccination for SARS-CoV-2, at 8 (+/- 2) weeks after the first vaccination (T1); and 6 and 12 months after the first vaccination (T2 and T3) using a validated immuno-assay for detection of SARS-CoV-2 IgG antibodies
Measured: Change from baseline to 8 weeks, 6 months and 12 months timepoint
Seroconversion
To document SARS-CoV-2 seroconversion among employees of the UZ Brussel after ChAdOx1 nCoV-19 vaccination for SARS-CoV-2, at 8 (+/- 2) weeks after the first vaccination (T1); and 6 and 12 months after the first vaccination (T2 and T3) using a validated immuno-assay for detection of SARS-CoV-2 IgG antibodies
Measured: Change from baseline to 8 weeks, 6 months and 12 months timepoint
Secondary outcomes (6)
SARS-CoV-2 seroprevalence before and after vaccination
To compare the SARS-CoV-2 seroprevalence before vaccination with the SARS-CoV-2 prevalence after vaccination among employees of the UZ Brussel.
Measured: Change from baseline to 8 weeks, 6 months and 12 months timepoint
incidence of new definite cases
To document the incidence of new definite cases of COVID-19 (based on self-reported positive PCR testing on nasopharyngeal swab) among vaccinated employees of the UZ Brussel over a period of a year.
Measured: Change from baseline to 8 weeks, 6 months and 12 months timepoint
incidence of new probable cases
To document the incidence of new probable cases of COVID-19 (based on the study questionnaire filled in by the participants) among vaccinated employees of the UZ Brussel over a period of a year.
Measured: Change from baseline to 8 weeks, 6 months and 12 months timepoint
antibody kinetics of the SARS-CoV-2 specific antibodies using immunassays
To document the SARS-CoV-2 antibody kinetics after vaccination.
Measured: Change from baseline to 8 weeks, 6 months and 12 months timepoint
antigen-specificity of the SARS-CoV-2-specific T cells
To determine the antigen-specificity of the SARS-CoV-2-specific T cells as well as their phenotype and functionality
Measured: Change from baseline to 8 weeks, 6 months and 12 months timepoint
antibody neutralisation capacity of the SARS-CoV-2 specific B cells using immunassays
To document the SARS-CoV-2 antibody neutralisation capacity after vaccination.
Measured: Change from baseline to 8 weeks, 6 months and 12 months timepoint
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted25 Jun 2021
- Study start5 May 2021
- Primary completionMay 2028 (estimated)
- Study completionJun 2028 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for SARS-CoV-2Studies of the same condition, open and under way.
- More trials run by Universitair Ziekenhuis BrusselThe 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
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Diagnosis
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Enrolment
- 200 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Universitair Ziekenhuis Brussel
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT04939402
- Sponsor's protocol ID
- COVEMUZ-3
- Status last verified
- Dec 2025
- First submitted
- 22 Apr 2021
- Last updated
- 18 Dec 2025
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 18 Dec 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- SARS-COV-2 Seroprevalence and Seroconversion Among Employees of the Universitair Ziekenhuis Brussel Following COVID-19 Vaccination Using an Adenoviral Vector
- ClinicalTrials.gov ID
- NCT04939402
- Acronym / sponsor ID
- COVEMUZ-3
- Conditions
- SARS-CoV-2, Covid19
- Study type
- Interventional
- Recruitment status
- Active, not recruiting
- Enrolment
- 200 participants (estimated)
- Lead sponsor
- Universitair Ziekenhuis BrusselUniversity, hospital or other
- Study start
- 5 May 2021 (actual)
- Primary completion
- May 2028 (estimated)
- Study completion
- Jun 2028 (estimated)
- First posted
- 25 Jun 2021 (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.
A novel zoonotic coronavirus was discovered in Wuhan (Hubei Province, China) mid-December 2019 and was named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The virus rapidly spread to the rest of the world, including Europe and explicitly affects the respiratory system, generating Coronavirus disease 2019 (COVID-19).
Employees of the university hospital of Brussels (UZ Brussel) presenting symptoms suggestive of COVID-19 are offered to be tested with real-time PCR on nasopharyngeal swabs. As asymptomatic infections have been described and as the PCR can be negative when taken late after onset of symptoms, serologic tests can be performed. The SARS-CoV 2003 epidemic demonstrated that serological assays were a useful diagnostic tool of non-acute infections. Although it is still uncertain whether convalescing patients have a risk of re-infection, recent data suggest that SARS-CoV-2 antibodies could protect at least for some time from subsequent viral exposures.
As the COVID-19 pandemic had devastating medical, economic and social consequences, safe and effective prophylactic vaccines were urgently needed. And thus several candidate vaccines against SARS-CoV-2 have been developed. The vaccination campaign of the health care workers of the UZ Brussel started mid January 2021. The first available vaccine was the BNT162b2 (Pfizer) vaccine. Early March 2021, in order to accelerate the vaccination of the UZ Brussel employees, the ChAdOx1 nCoV-19 (AZD12222) (Oxford, AstaZeneca) vaccination program was implemented in parallel with the BNT162b2 vaccination program In the COVEMUZ-2 study the investigators have already started to document the SARS-CoV-2 seroprevalence and seroconversion among vaccinated employees (using BNT162b2) in the UZ Brussels.
In this study, the investigators aim to prospectively document the SARS-CoV-2 seroprevalence and seroconversion among vaccinated employees (using ChAdOx1 nCoV-19) of the UZ Brussel, at three different time points, namely 6 weeks (+/- 2 weeks; T1), 6 months (+/- 1 month; T2) and 12 months (+/- 1 month; T3) after the second vaccination.
Detailed description
A novel zoonotic coronavirus was discovered in Wuhan (Hubei Province, China) mid-December 2019 and was named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The virus rapidly spread to the rest of the world, including Europe and explicitly affects the respiratory system, generating Coronavirus disease 2019 (COVID-19).
Employees of the university hospital of Brussels (UZ Brussel) presenting symptoms suggestive of COVID-19 are offered to be tested with real-time PCR on nasopharyngeal swabs. As asymptomatic infections have been described and as the PCR can be negative when taken late after onset of symptoms, serologic tests can be performed. The SARS-CoV 2003 epidemic demonstrated that serological assays were a useful diagnostic tool of non-acute infections. Although it is still uncertain whether convalescing patients have a risk of re-infection, recent data suggest that SARS-CoV-2 antibodies could protect at least for some time from subsequent viral exposures.
As the COVID-19 pandemic had devastating medical, economic and social consequences, safe and effective prophylactic vaccines were urgently needed. And thus several candidate vaccines against SARS-CoV-2 have been developed. The vaccination campaign of the health care workers of the UZ Brussel started mid January 2021. The first available vaccine was the BNT162b2 (Pfizer) vaccine. Early March 2021, in order to accelerate the vaccination of the UZ Brussel employees, the ChAdOx1 nCoV-19 (AZD12222) (Oxford, AstaZeneca) vaccination program was implemented in parallel with the BNT162b2 vaccination program In the COVEMUZ-2 study the investigators have already started to document the SARS-CoV-2 seroprevalence and seroconversion among vaccinated employees (using BNT162b2) in the UZ Brussels.
In this study, the investigators aim to prospectively document the SARS-CoV-2 seroprevalence and seroconversion among vaccinated employees (using ChAdOx1 nCoV-19) of the UZ Brussel, at three different time points, namely 6 weeks (+/- 2 weeks; T1), 6 months (+/- 1 month; T2) and 12 months (+/- 1 month; T3) after the second vaccination.
Study design
- Primary purpose
- Diagnosis
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| General | Other | Diagnostic Test: Serological testingAll patients follow this arm. Patients will undergo 3 blood sample testings at 3 different time points and have to fill in a questionnaire at 3 different time points |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (1 listed)
- Any adult employee of the UZ Brussel at T1 who has been vaccinated at the UZ Brussel with ChAdOx1 nCoV-19 vaccine between the 2nd of March and the 9th of March 2021 after participating to phase 4 of the COVEMUZ study between the 25th of January and the 12th of February and has provided a signed informed consent.
Key exclusion criteria (1 listed)
- UZ Brussel employees not active during the inclusion period (T1).
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Serological testingAntibody testing for Sars-CoV-2 specific antibodies in blood + T cell immunity | Diagnostic test | General |
Primary outcome
Seroprevalence
Time frame: Change from baseline to 8 weeks, 6 months and 12 months timepoint
To document SARS-CoV-2 seroprevalence among employees of the UZ Brussel after ChAdOx1 nCoV-19 vaccination for SARS-CoV-2, at 8 (+/- 2) weeks after the first vaccination (T1); and 6 and 12 months after the first vaccination (T2 and T3) using a validated immuno-assay for detection of SARS-CoV-2 IgG antibodies
Seroconversion
Time frame: Change from baseline to 8 weeks, 6 months and 12 months timepoint
To document SARS-CoV-2 seroconversion among employees of the UZ Brussel after ChAdOx1 nCoV-19 vaccination for SARS-CoV-2, at 8 (+/- 2) weeks after the first vaccination (T1); and 6 and 12 months after the first vaccination (T2 and T3) using a validated immuno-assay for detection of SARS-CoV-2 IgG antibodies
6 secondary outcomes
SARS-CoV-2 seroprevalence before and after vaccination
Time frame: Change from baseline to 8 weeks, 6 months and 12 months timepoint
incidence of new definite cases
Time frame: Change from baseline to 8 weeks, 6 months and 12 months timepoint
incidence of new probable cases
Time frame: Change from baseline to 8 weeks, 6 months and 12 months timepoint
antibody kinetics of the SARS-CoV-2 specific antibodies using immunassays
Time frame: Change from baseline to 8 weeks, 6 months and 12 months timepoint
antigen-specificity of the SARS-CoV-2-specific T cells
Time frame: Change from baseline to 8 weeks, 6 months and 12 months timepoint
antibody neutralisation capacity of the SARS-CoV-2 specific B cells using immunassays
Time frame: Change from baseline to 8 weeks, 6 months and 12 months timepoint
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 18 Dec 2025.
- Individual participant dataSharing planned: No
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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?
A study testing Serological testing in people with SARS-CoV-2 and Covid19, run by Universitair Ziekenhuis Brussel at 1 site in Belgium.
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 1 inclusion and 1 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 18 Dec 2025. 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 Belgium. 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?
Seroprevalence (time frame: Change from baseline to 8 weeks, 6 months and 12 months timepoint). 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 18 Dec 2025.