An observational study in Monkeypox, sponsored by Institute of Tropical Medicine, Belgium. Recruiting at 1 site in Belgium. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-03-19.
Sponsored by Institute of Tropical Medicine, Belgium · Observational
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:
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.
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)
72 studies on the registry are indexed under Mpox, Monkeypox; 30 are open to participants now.
This study's planned enrollment of 345 is above the median of 224 across 34 observational studies indexed under Mpox, Monkeypox.
Browse Mpox, Monkeypox studies →Institute of Tropical Medicine, Belgium is the lead sponsor of 104 studies on the registry; 21 are open to participants now.
Counted across the registry records on this site, refreshed daily.
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
Mpox patients for immunological study
Inclusion criteria
Exclusion criteria
Smallpox vaccinees for immunological study
Inclusion criteria
Exclusion criteria
HIV-Prep patients
Inclusion criteria
Exclusion criteria
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
HIV
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
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
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
50 controls recruited during HIV-PrEP consultation (no former mpox infection, no smallpox vaccination)
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
Time frame: 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
Time frame: 2 years
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
Time frame: 2 years
Plan to share: Undecided
No publications or documents are linked to this record.
Eligibility is decided by the study team. Share this record with your doctor or contact the team directly.
Contact study teamGet an email when the registry record changes — status, dates, results — or when someone posts here.
Sign in to followQuestions and observations about this study, from anyone following it. Not medical advice, and not a channel to the study team — their contact details are on the registry record.
Sign in to join the discussion. Reading takes no account; posting does. You choose a display name, and a pseudonym is the default.
Nothing here yet. If you are running this trial, taking part in it, or weighing whether to, this is the place to say so.
Institute of Tropical Medicine, Belgium →