Mpox Biology, Outcome, Transmission and Epidemiology - Tracking the Immune Response After mpoX vaCcination (MBOTE-TRAXX): Clinical Study to Monitor the Immunological Response Following Mpox Vaccination in the City of Kinshasa, Democratic Republic of the Congo (MBOTE-TRAXX)

Mpox Biology, Outcome, Transmission and Epidemiology - Tracking the Immune Response After mpoX vaCcination

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.

Study Overview

• Status: Active, not recruiting
• Conditions: Mpox
• Intervention / Treatment: Procedure: blood sample collection

Detailed Description

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.

• Study Type: Interventional
• Enrollment (Estimated): 300
• Phase: Phase 4

Contacts and Locations

Study Locations

• Democratic Republic of the Congo
  • Kinshasa, Democratic Republic of the Congo
    • Centre Convivial Kasa-Vubu
  • Kinshasa, Democratic Republic of the Congo
    • Kinoise
  • Kinshasa, Democratic Republic of the Congo
    • Kokolo

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• Any person aged 18 years old or over at the time of giving informed consent, of any gender
• Participant received the MVA-BN or LC16m8 mpox vaccine as part of the national vaccination campaign
• Participant has the capacity and willingness to give informed written consent
• Participant agrees to adhere to the study's follow-up schedule

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Other: MVA-BN or LC16m8 vaccinated; 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.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
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	Day 28 after inclusion

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
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.	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).	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.	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.	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).	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).	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.	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).	Month 24

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
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.	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	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	Day 0, Day 28, Day 59, Month 8, Month 16, and Month 24

Collaborators and Investigators

• Sponsor: Institute of Tropical Medicine, Belgium
• Collaborators: Institut National de Recherche Biomédicale (INRB). Kinshasa, Democratic Republic of Congo; Programme Elargi de Vaccination de République Démocratique du Congo; National Institute of Public Health of the Democratic Republic of the Congo

Study record dates

Study Major Dates

• Study Start (Actual): May 15, 2026
• Primary Completion (Estimated): December 15, 2026
• Study Completion (Estimated): December 15, 2028

Study Registration Dates

• First Submitted: March 24, 2026
• First Submitted That Met QC Criteria: March 24, 2026
• First Posted (Actual): March 30, 2026

Study Record Updates

• Last Update Posted (Actual): June 11, 2026
• Last Update Submitted That Met QC Criteria: June 9, 2026
• Last Verified: June 1, 2026

More Information

Terms related to this study

• Keywords: mpox vaccines
• Additional Relevant MeSH Terms: Infections; Virus Diseases; Poxviridae Infections; DNA Virus Infections; Animal Diseases; Primate Diseases; Rodent Diseases; Mpox, Monkeypox
• Other Study ID Numbers: 1998/26

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No