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NCT Number: NCT07499739

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

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.

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This study is active but is not currently recruiting participants.

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Key information

Conditions

Mpox Animal Diseases DNA Virus Infections Infections Mpox, Monkeypox Poxviridae Infections Primate Diseases Rodent Diseases Virus Diseases

Age range

18 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Phase 4

Primary location

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

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About this study

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.

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

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

Treatment and study plan

blood sample collection

Procedure

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.

Primary outcomes

  1. 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)

    Time frame: Day 28 after inclusion

    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

Secondary outcomes

  1. 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).

    Time frame: Day 59 and Month 8

    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.

  2. 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).

    Time frame: Day 0, Day 28, Day 59 and Month 8

    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).

  3. 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).

    Time frame: Day 0, Day 28, Day 59, Month 8, Month 16 and Month 24

    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.

  4. 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).

    Time frame: Day 0, Day 28, Day 59, Month 8, Month 16, and Month 24

    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.

  5. 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).

    Time frame: Day 0, Day 28, Day 59, and Month 8

    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).

  6. 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).

    Time frame: Day 0, Day 28, Day 59, Month 8, Month 16, and Month 24

    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).

  7. To evaluate the tolerability of MVA-BN and LC16m8 vaccines in terms of solicited symptoms occurring up to 28 days after vaccination.

    Time frame: Day 28

    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.

  8. To document post-vaccination mpox virus infections after administration of an mpox vaccine (MVA-BN or LC16m8).

    Time frame: Month 24

    Number of post-vaccination mpox infections. Post-vaccination mpox infections are defined as any laboratory-confirmed mpox infection occurring after vaccination (assessed anamnesticly).

Other outcomes

  1. 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.

    Time frame: 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.

  2. 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.

    Time frame: Day 0, Day 28, Day 59, Month 8, Month 16, and Month 24

    • 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

  3. 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.

    Time frame: Day 0, Day 28, Day 59, Month 8, Month 16, and Month 24

    • 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

Sponsors and collaborators

Lead sponsor

Institute of Tropical Medicine, Belgium

Other

Collaborators

  • Institut National de Recherche Biomédicale. Kinshasa, République Démocratique du Congo
  • National Institute of Public Health of the Democratic Republic of the Congo
  • Programme Elargi de Vaccination de République Démocratique du Congo

Registry information

Official study title

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

Acronym: MBOTE-TRAXX

Important dates

Study start
2026
Primary completion
2026
Study completion
2028
First posted
Mar 30, 2026
Registry last updated
Jun 11, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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