A Phase 4 interventional study of blood sample collection in Mpox, sponsored by Institute of Tropical Medicine, Belgium. Active, not recruiting at 3 sites in Democratic Republic of the Congo. Open to participants aged 18 Years and older, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-06-11.
Sponsored by Institute of Tropical Medicine, Belgium · Phase 4, Interventional, and Treatment
The study Mbote-TRAXX evaluates humoral and cellular immune responses in individuals vaccinated against mpox with the MVA-BN or LC16m8 vaccine administered as part of a routine mpox vaccination campaign in Kinshasa, Democratic Republic of the Congo (DRC). Participants will be followed up at multiple time points after vaccination in order to assess the kinetics and durability of the immune response by collection of blood samples. It is planned to include approximately 150 participants vaccinated with MVA-BN and 150 participants vaccinated with LC16m8.
The study Mbote-TRAXX evaluates humoral and cellular immune responses in individuals vaccinated against mpox with the MVA-BN or LC16m8 vaccine administered as part of a routine mpox vaccination campaign in Kinshasa, Democratic Republic of the Congo (DRC). Participants will be followed up at multiple time points after vaccination in order to assess the kinetics and durability of the immune response. It is planned to include approximately 150 participants vaccinated with MVA-BN and 150 participants vaccinated with LC16m8. Participants will be followed up in the clinical trial for a period of 24 months with 6 visits: visit 1 (day 0), visit 2 (day 0 + 28 days), visit 3 (day 0 + 59 days), visit 4 (day 0 + 8 months), visit 5 (day 0 + 16 months) and visit 6 (day 0 + 24 months). The study intervention consists of blood samples. At each visit, 10 mL of blood will be collected, and additional blood samples (20 mL per visit) will be taken from a subgroup of participants.
72 studies on the registry are indexed under Mpox, Monkeypox; 30 are open to participants now.
This study's planned enrollment of 300 is close to the median of 305 across 36 interventional 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.
Inclusion 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.
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.
Participants vaccinated with MVA-BN or LC16m8 vaccine during the national vaccination campaign
Procedure: blood sample collection
10 mL of blood will be collected at every visit and additional 20 mL blood samples will be taken from a subgroup of participants at every visit.
To estimate the seroconversion rate for neutralising antibodies against the mpox virus (MPXV) 28 days after administration of an mpox vaccine (MVA-BN or LC16m8)
Seroconversion 28 days after administration of an mpox vaccine, defined as the appearance of an MPXV neutralizing antibody titer (NT50) greater than or equal to the limit of detection in participants who were seronegative at baseline, or at least a two-fold increase in the antibody titer compared to baseline (Day 0) in participants who were seropositive at inclusion
Time frame: Day 28 after inclusion
To estimate the positivity rate for neutralizing antibodies against MPXV 59 days and 8 months after administration of an mpox vaccine (MVA-BN or LC16m8).
Positivity rate 59 days and 8 months after administration of an mpox vaccine (MVA-BN or LC16m8), defined as the appearance of an MPXV neutralizing antibody titer (NT50) greater than or equal to the limit of detection for participants who were initially seronegative, or by a two-fold increase or more in antibody titer compared with the value at Day 0 in participants who were seropositive at enrollment.
Time frame: Day 59 and Month 8
To analyze the longitudinal evolution of neutralizing antibody titers against MPXV between Day 0, Day 28, Day 59, and Month 8 after administration of an mpox vaccine (MVA-BN or LC16m8).
Neutralizing antibody titers against MPXV measured at Day 0, Day 28, Day 59, and Month 8 after administration of an mpox vaccine (MVA-BN or LC16m8).
Time frame: Day 0, Day 28, Day 59 and Month 8
To estimate the positivity rate for binding antibodies (IgG) against MPXV at all sampling time points: Day 0, Day 28, Day 59, Month 8, Month 16, and Month 24 after administration of an mpox vaccine (MVA-BN or LC16m8).
Positivity rate at Day 28, Day 59, Month 8, Month 16, and Month 24 after administration of an mpox vaccine (MVA-BN or LC16m8). The positivity rate is defined by the appearance of median fluorescence intensity (MFI) values greater than the limit of detection for participants who were initially seronegative, or by more than a two-fold increase in antibody titer compared with the value at Day 0 for participants who were seropositive at baseline.
Time frame: Day 0, Day 28, Day 59, Month 8, Month 16 and Month 24
To analyze the longitudinal evolution of binding antibody (IgG) titers against MPXV between Day 0, Day 28, Day 59, Month 8, Month 16, and Month 24 after administration of an mpox vaccine (MVA-BN or LC16m8).
Binding antibody (IgG) titers against MPXV measured at Day 28, Day 59, Month 8, Month 16, and Month 24 after administration of an mpox vaccine (MVA-BN or LC16m8), compared with binding antibody (IgG) titers at Day 0.
Time frame: Day 0, Day 28, Day 59, Month 8, Month 16, and Month 24
To identify factors associated with weak immune responses, measured by the seroconversion rate of neutralizing antibodies at Day 0, Day 28, Day 59, and Month 8 after administration of an mpox vaccine (MVA-BN or LC16m8).
Seroconversion at Day 0, Day 28, Day 59, and Month 8 after administration of an mpox vaccine (MVA-BN or LC16m8). The association between risk factors and neutralizing antibody titers will be assessed using logistic regression (or mixed-effects logistic regression for the longitudinal analysis).
Time frame: Day 0, Day 28, Day 59, and Month 8
To identify factors associated with weak immune responses, measured by the seroconversion rate of binding antibodies (IgG) at Day 0, Day 28, Day 59, Month 8, Month 16, and Month 24 after administration of an mpox vaccine (MVA-BN or LC16m8).
Seroconversion at Day 0, Day 28, Day 59, Month 8, Month 16, and Month 24 after administration of an mpox vaccine (MVA-BN or LC16m8). The association between risk factors and binding antibody (IgG) titers will be assessed using logistic regression (or mixed-effects logistic regression for the longitudinal analysis).
Time frame: Day 0, Day 28, Day 59, Month 8, Month 16, and Month 24
To evaluate the tolerability of MVA-BN and LC16m8 vaccines in terms of solicited symptoms occurring up to 28 days after vaccination.
The frequency of solicited local symptoms (pain, redness, swelling, induration, itching, or a distinct mark \[only for the LC16m8 vaccine\] at the injection site) and solicited systemic symptoms (headache, fatigue, nausea, vomiting, generalized muscle pain, chills, and/or fever greater than or equal to 38.0°C) up to Day 28 after vaccination.
Time frame: Day 28
To document post-vaccination mpox virus infections after administration of an mpox vaccine (MVA-BN or LC16m8).
Number of post-vaccination mpox infections. Post-vaccination mpox infections are defined as any laboratory-confirmed mpox infection occurring after vaccination (assessed anamnesticly).
Time frame: Month 24
To determine, in a subgroup, the T-cell response induced by the MVA-BN or LC16m8 vaccine at Day 0, Day 28, Day 59, Month 8, Month 16, and Month 24.
Number or frequency of MPXV-specific T lymphocytes at Day 0, Day 28, Day 59, Month 8, Month 16, and Month 24.
Time frame: Day 0, Day 28, Day 59, Month 8, Month 16, and Month 24
To compare the seroconversion rates of neutralizing antibodies and binding antibodies (IgG) against MPXV, and of vaccine-induced T lymphocytes, between participants vaccinated with MVA-BN versus LC16m8.
* Difference between the seroconversion rates of binding antibodies (IgG) against MPXV at Day 0, Day 28, Day 59, Month 8, Month 16, and Month 24, between participants vaccinated with MVA-BN and LC16m8 * Difference between the seroconversion rates of neutralizing antibodies against MPXV at Day 0, Day 28, Day 59, and Month 8 between participants vaccinated with MVA-BN and LC16m8 Difference between the number or frequency of MPXV-specific T lymphocytes at Day 0, Day 28, Day 59, Month 8, Month 16, and Month 24 between subjects vaccinated with MVA-BN and LC16m8
Time frame: Day 0, Day 28, Day 59, Month 8, Month 16, and Month 24
To compare the seroconversion rates of neutralizing antibodies and binding antibodies (IgG) against MPXV, and of vaccine-induced T lymphocytes, between naïve participants and those with a history of smallpox/mpox vaccination or prior mpox infection.
* Differences between the seroconversion rates of binding antibodies (IgG) against MPXV at Day 0, Day 28, Day 59, Month 8, Month 16, and Month 24, between naïve participants and participants pre-immunized by mpox infection or by prior smallpox/mpox vaccination * Differences between the seroconversion rates of neutralizing antibodies against MPXV at Day 0, Day 28, Day 59, and Month 8 between naïve participants and participants pre-immunized by mpox infection or by prior smallpox/mpox vaccination * Difference between the number or frequency of MPXV-specific T lymphocytes at Day 0, Day 28, Day 59, Month 8, Month 16, and Month 24 between naïve participants and participants pre-immunized by mpox infection or by prior smallpox/mpox vaccination
Time frame: Day 0, Day 28, Day 59, Month 8, Month 16, and Month 24
Plan to share: No
No publications or documents are linked to this record.
Started May 2026 (actual). Primary completion is estimated for Dec 2026, 7 months after the start.
How these figures are worked out, and which studies are left out of them.
This study is active, not recruiting, as verified in Jun 2026. You cannot join it, but the record below documents what was studied.
Get 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 →