MonkeypoxPOQS-FU PLUSNCT05879965
Prospective Study for the FOLLOW-UP of Human Monkeypox Cases and Smallpox Vaccinees at Risk
An observational study of Monkeypox, run by Institute of Tropical Medicine, Belgium at 1 site in Belgium.
Trial summary
The goal of this observational study is to describe possible physical and psychological sequelae after an mpox infection and to evaluate the longevity of B- and T-cell immune responses in former mpox patients and vaccine recipients. Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Monkeypox
- Type of treatment
- Vaccines, Injection or infusion
- How many people
- 345 participants
- Where
- 1 siteBelgium
- Study dates
- 6 Oct 2022to Jun 2028
- 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 18 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Study population: Former mpox patients ≥18 years, diagnosed by PCR at ITM since May 2022 Smallpox vaccine recipients vaccinated at ITM since August 2022 Healthy HIV-PrEP users
Who may be able to join
- PCR-confirmed mpox infection since May 2022
- ≥18 years
- Willingness to provide written informed consent
- Willingness to follow the study schedule
- At least two smallpox vaccinations.
- ≥18 years
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- Willingness to provide written informed consent
- Willingness to follow the study schedule
- On HIV-PrEP and a patient from ITM
- ≥18 years
- Willingness to provide written informed consent
- Willingness to follow the study schedule
Who cannot join
- Any vaccination 2 weeks before or after the visits (4 weeks for life-vaccines)
- Any immune-compromising drugs or diseases (treated and controlled HIV-infection is no exclusion criteria)
- Any mpox reinfection since study start
- Smallpox vaccinees for immunological study
- Any vaccination 2 weeks before or after the visits (4 weeks for life-vaccines)
- Any immune-compromising drugs or diseases (treated and controlled HIV-infection is no exclusion criteria)
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- Any mpox infection in the past
- HIV-Prep patients
- Born before 1976
- Any documented or remembered smallpox vaccination or typical scar for a smallpox vaccination
- Any vaccination 2 weeks before or after the visits (4 weeks for life-vaccines)
- Any immune-compromising drugs or diseases
- Any mpox infection in the past
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Belgium1 site, 1 recruiting
- Recruiting
Institute of Tropical Medicine
Antwerp, 2000
Yven Van Herrewege, +32(0)33455557, yvanherrewege@itg.be
About this study
Official title: Prospective On-site and Questionnaire Study for the FOLLOW-UP of Mpox Cohort at ITM PLUS Evaluation of the Longevity of B- and T-cell Immune Responses in Former Mpox Patients and Vaccine Recipients
The goal of this observational study is to describe possible physical and psychological sequelae after an mpox infection and to evaluate the longevity of B- and T-cell immune responses in former mpox patients and vaccine recipients.
The main questions it aims to answer are:
Read more
- Are there any physical or pschological sequelae after mpox infection?
- Is the humoral and/or cellular immune response to MPOX (or vaccinia) virus) durable?
- Do the patients develop strong local immunity in comparison to systemic immunity?
- How long is the virus still detectable in semen, saliva or the ano-rectal region?
Participants will answer a questionnaire, samples with blood, saliva and semen as well as anal swabs will be collected. Follow-up visits 8, 16 and 24, 36, 48, and 60 months after infection or vaccination are planned.
A healthy control group will be recruited in our HIV-PrEP clinic.
Read the detailed description
Long-term problems or sequelae after an acute viral infection are described. The study aim is to investigate if long-term symptoms and sequelae can be found in the ITM human mpox infection cohort previously diagnosed and confirmed by PCR at the Institute of Tropical Medicine in Antwerp during the mpox outbreak 2022 in Belgium. The immune response after a natural mpox infection and after a smallpox vaccination will additionally analysed over time.
Consented participants Mpox patients, acute infection (n=169, 21% assumed smallpox vaccination in childhood) Mpox patients for follow-up (n=95, 20% assumed smallpox vaccination in childhood) Smallpox vaccinees, two intradermal doses (n=100) Smallpox vaccinees, two subcutaneous doses (n=100) Healthy unvaccinated controls (n=50)
Design This prospective longitudinal study has the main objectives to describe possible physical and psychological sequelae after an mpox infection and to evaluate the longevity of B- and T-cell immune responses in former mpox patients and vaccine recipients. Participants are being followed up 8, 16 and 24 months after infection or vaccination.
Sample collection Anal eSwabs from patients, controls and vaccinees Saliva (Omnigene-oral and dry swabs) from patients, controls and vaccinees Serum from patients, controls and vaccinees Optional semen samples from patients PBMC samples from a sub-group of patients, controls and vaccinees
Laboratory analysis MPXV-PCR on saliva, anorectal and optional semen samples of former mpox patients, vaccinated individuals and healthy controls Mpox-specific antibody profiling from serum Mucosal immunity (IgA, IgG) mpox-specific/reactive from anal swabs and/or saliva Enumeration of MPXV-specific effector-memory T cells via flow cytometry-based AIM or ICS assays (peptide pool stimulation or HLA-restricted multimer-based capture assays) Enumeration of MPXV-specific memory B cells or plasma cells via flow cytometry-ased AIM or ICS assays (recombinant antigen stimulation or HLA-restricted multimer-based capture assays)
- Conditions
- Monkeypox
- Keywords
- mpox, immunology, mucosal immunity, sequelae, smallpox vaccination
- Medical subject headings
- Mpox, Monkeypox
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
| Study group | Role | What they receive |
|---|---|---|
| mpox patients | mpox cohort diagnosed and confirmed by PCR at the Institute of Tropical Medicine (ITM) in Antwerp during the recent mpox outbreak May-October 2022, 95 consented patients for follow-up | |
| Smallpox vaccine recipients | sub-group 1: 100 participants routinely vaccinated with two subcutaneous 3rd generation smallpox vaccines sub-group 2: 100 participants routinely vaccinated with two intradermal 3rd generation smallpox vaccines | |
| Healthy controls | 50 controls recruited during HIV-PrEP consultation (no former mpox infection, no smallpox vaccination) |
What is being measured
The primary outcome is the main question the study is designed to answer.
Proportion of individuals with a positive mpox serology in both groups
To compare the MPXV-specific serological response in naturally infected mpox male patients 8, 16 and 24 months after onset of symptoms with the MPXV-specific serological response in routinely (=2 either subcutaneous (SC) or intradermal (ID) vaccinations with an interval of 4-8 weeks) vaccinated men against smallpox 8 months after the first vaccination
Measured: 2 years
Proportion of long-term problems or sequelae in mpox patients
To describe any possible long-term problem or sequela after an acute human mpox infection diagnosed and confirmed by PCR at ITM since the beginning of the mpox outbreak End of May 2022
Measured: 2 years
Secondary outcomes (1)
longevity of humoral and/or cellular immune response to mpox or vaccinia virus
B-cell and T-cell characteristics in former mpox patients and smallpox vaccinees 8, 16, 24 months after symptom
Measured: 2 years
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted30 May 2023
- Study start6 Oct 2022
- Primary completionOct 2027 (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 MonkeypoxStudies of the same condition, open and under way.
- 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
- 345 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Institute of Tropical Medicine, Belgium
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
- Investigators
- Nicole Berens-Riha, PhD, Principal investigator, Institute of Tropical MedicineLaurens Liesenborghs, PhD, Study director, Institute of Tropical Medicine
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05879965
- Sponsor's protocol ID
- 1628/22
- Acronym
- POQS-FU PLUS
- Status last verified
- Mar 2026
- First submitted
- 19 May 2023
- Last updated
- 19 Mar 2026
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Undecided
Study at a glance
From the registry record, last updated by the sponsor on 19 Mar 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Prospective On-site and Questionnaire Study for the FOLLOW-UP of Mpox Cohort at ITM PLUS Evaluation of the Longevity of B- and T-cell Immune Responses in Former Mpox Patients and Vaccine Recipients
- ClinicalTrials.gov ID
- NCT05879965
- Acronym / sponsor ID
- POQS-FU PLUS / 1628/22
- Conditions
- Monkeypox
- Keywords
- mpox, immunology, mucosal immunity, sequelae, smallpox vaccination
- Study type
- Observational
- Recruitment status
- Recruiting
- Enrolment
- 345 participants (estimated)
- Lead sponsor
- Institute of Tropical Medicine, BelgiumUniversity, hospital or other
- Study start
- 6 Oct 2022 (actual)
- Primary completion
- Oct 2027 (estimated)
- Study completion
- Jun 2028 (estimated)
- First posted
- 30 May 2023 (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 goal of this observational study is to describe possible physical and psychological sequelae after an mpox infection and to evaluate the longevity of B- and T-cell immune responses in former mpox patients and vaccine recipients.
The main questions it aims to answer are:
- Are there any physical or pschological sequelae after mpox infection?
- Is the humoral and/or cellular immune response to MPOX (or vaccinia) virus) durable?
- Do the patients develop strong local immunity in comparison to systemic immunity?
- How long is the virus still detectable in semen, saliva or the ano-rectal region?
Participants will answer a questionnaire, samples with blood, saliva and semen as well as anal swabs will be collected. Follow-up visits 8, 16 and 24, 36, 48, and 60 months after infection or vaccination are planned.
A healthy control group will be recruited in our HIV-PrEP clinic.
Detailed description
Long-term problems or sequelae after an acute viral infection are described. The study aim is to investigate if long-term symptoms and sequelae can be found in the ITM human mpox infection cohort previously diagnosed and confirmed by PCR at the Institute of Tropical Medicine in Antwerp during the mpox outbreak 2022 in Belgium. The immune response after a natural mpox infection and after a smallpox vaccination will additionally analysed over time.
Consented participants Mpox patients, acute infection (n=169, 21% assumed smallpox vaccination in childhood) Mpox patients for follow-up (n=95, 20% assumed smallpox vaccination in childhood) Smallpox vaccinees, two intradermal doses (n=100) Smallpox vaccinees, two subcutaneous doses (n=100) Healthy unvaccinated controls (n=50)
Design This prospective longitudinal study has the main objectives to describe possible physical and psychological sequelae after an mpox infection and to evaluate the longevity of B- and T-cell immune responses in former mpox patients and vaccine recipients. Participants are being followed up 8, 16 and 24 months after infection or vaccination.
Sample collection Anal eSwabs from patients, controls and vaccinees Saliva (Omnigene-oral and dry swabs) from patients, controls and vaccinees Serum from patients, controls and vaccinees Optional semen samples from patients PBMC samples from a sub-group of patients, controls and vaccinees
Laboratory analysis MPXV-PCR on saliva, anorectal and optional semen samples of former mpox patients, vaccinated individuals and healthy controls Mpox-specific antibody profiling from serum Mucosal immunity (IgA, IgG) mpox-specific/reactive from anal swabs and/or saliva Enumeration of MPXV-specific effector-memory T cells via flow cytometry-based AIM or ICS assays (peptide pool stimulation or HLA-restricted multimer-based capture assays) Enumeration of MPXV-specific memory B cells or plasma cells via flow cytometry-ased AIM or ICS assays (recombinant antigen stimulation or HLA-restricted multimer-based capture assays)
Study design
- Observational model
- Cohort
- Time perspective
- Prospective
- Number of arms
- 3
| Arm | Type | Receives |
|---|---|---|
| mpox patients | – | –mpox cohort diagnosed and confirmed by PCR at the Institute of Tropical Medicine (ITM) in Antwerp during the recent mpox outbreak May-October 2022, 95 consented patients for follow-up |
| Smallpox vaccine recipients | – | –sub-group 1: 100 participants routinely vaccinated with two subcutaneous 3rd generation smallpox vaccines sub-group 2: 100 participants routinely vaccinated with two intradermal 3rd generation smallpox vaccines |
| Healthy controls | – | –50 controls recruited during HIV-PrEP consultation (no former mpox infection, no smallpox vaccination) |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
- Study population
- Former mpox patients ≥18 years, diagnosed by PCR at ITM since May 2022 Smallpox vaccine recipients vaccinated at ITM since August 2022 Healthy HIV-PrEP users
Key inclusion criteria (12 listed)
- PCR-confirmed mpox infection since May 2022
- ≥18 years
- Willingness to provide written informed consent
- Willingness to follow the study schedule
- At least two smallpox vaccinations.
Key exclusion criteria (13 listed)
- Any vaccination 2 weeks before or after the visits (4 weeks for life-vaccines)
- Any immune-compromising drugs or diseases (treated and controlled HIV-infection is no exclusion criteria)
- Any mpox reinfection since study start
- Smallpox vaccinees for immunological study
- Any vaccination 2 weeks before or after the visits (4 weeks for life-vaccines)
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 individuals with a positive mpox serology in both groups
Time frame: 2 years
To compare the MPXV-specific serological response in naturally infected mpox male patients 8, 16 and 24 months after onset of symptoms with the MPXV-specific serological response in routinely (=2 either subcutaneous (SC) or intradermal (ID) vaccinations with an interval of 4-8 weeks) vaccinated men against smallpox 8 months after the first vaccination
Proportion of long-term problems or sequelae in mpox patients
Time frame: 2 years
To describe any possible long-term problem or sequela after an acute human mpox infection diagnosed and confirmed by PCR at ITM since the beginning of the mpox outbreak End of May 2022
1 secondary outcome
longevity of humoral and/or cellular immune response to mpox or vaccinia virus
Time frame: 2 years
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 19 Mar 2026.
- Individual participant dataSharing planned: Undecided
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New York City Observational Study of Mpox Immunity
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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.
Nicole Berens-Riha, PhD principal investigator
Institute of Tropical Medicine
Laurens Liesenborghs, PhD study director
Institute of Tropical Medicine
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 Monkeypox, run by Institute of Tropical Medicine, Belgium 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 12 inclusion and 13 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: looking for participants now, as of the sponsor's last update on 19 Mar 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 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?
Contact Study Coordinator (+32(0)33455672, bsmekens@itg.be), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Proportion of individuals with a positive mpox serology in both groups (time frame: 2 years). 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 19 Mar 2026.