Mpox (Monkeypox)NCT06984705
Epidemiological and Clinical Characteristics of Human Mpox Outbreak in Equateur Province in the Democratic Republic of Congo (Part3)
An observational study of Mpox (Monkeypox), run by Osaka Metropolitan University at 1 site in Democratic Republic of the Congo.
Trial summary
The goal of this study is to evaluate the effectiveness of smallpox vaccination administered before the global eradication of smallpox against currently circulating mpox in the Democratic Republic of the Congo. Read more about this study
- Who is it for?
- Any age
- Conditions the study is for
- Mpox (Monkeypox)
- How many people
- 144 participants
- Where
- 1 siteDemocratic Republic of the Congo
- Study dates
- 31 Jul 2025to 31 Jul 2025
- 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 Any age
- All sexes
- No healthy volunteers
- Child, Adult, Older adult
Study population: This study targets patients born before 1984 with mpox-like skin lesions (both sexes) in the selected sites. All patients suspected of having mpox-like lesions and who provide proxy-assisted written informed consent to participate in the study are eligible for inclusion due to reduction of the risk of contact transmission with verbal agreement documented and confirmed by a witness. This approach prioritizes participant and staff safety while adhering to ethical standards.
Who may be able to join
- Individuals born before 1984: Although it is officially stated that smallpox vaccination was administered in the DRC until 1982, individuals born up to 1984 were included to account for potential discrepancies of several years in remote areas.
- Presence of skin lesions suspected to be mpox.
- Provision of informed consent:
- Proxy-assisted informed consent is allowed under safety considerations. Following oral consent, the investigator will document this on the informed consent form as a witness.
Who cannot join
- Participants will be excluded from the study under the following conditions:
- Refusal to participate in the study: Individuals who decline to provide consent for study participation will be excluded.
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Democratic Republic of the Congo1 site
Equateur Provincial Public Health Laboratory
Mbandaka, Équateur Province
About this study
The goal of this study is to evaluate the effectiveness of smallpox vaccination administered before the global eradication of smallpox against currently circulating mpox in the Democratic Republic of the Congo.
The main question it aims to answer is:
Is the smallpox vaccine experience protective against mpox infection ?
Researchers will compare mpox test positive group and negative group to see if the smallpox vaccine can protect against mpox infection.
Participants will
- be included after informed consent,
- respond the survey with structured questionnaire
- and accept skin lesion and blood sampling.
Read the detailed description
Mpox is caused by the monkeypox virus (MPXV), a member of the genus Orthopoxvirus (family Poxviridae). This virus is closely related to the variola virus, which causes smallpox. MPXV was first identified in 1958, and the first human case was reported in Democratic Republic of the Congo (DRC) in 1970. It was presumed that the smallpox vaccine would confer cross-protection against mpox. Following the global eradication of smallpox in 1980, mpox remained largely confined to limited regions in Central Africa-where zoonotic spillover from wild animal reservoirs constituted the primary route of transmission. Equateur Province is among the areas in the DRC with a notably high burden of reported mpox cases.
Over the past five decades, routine smallpox vaccination ceased worldwide, resulting in waning herd immunity against orthopoxviruses. During this period, mpox incidence rose markedly, with an estimated tenfold increase in global cases. Two principal genetic clades of MPXV have been identified: clade I (historically referred to as the Congo Basin clade) and clade II (the West African clade). In 2018, Nigeria experienced a resurgence of mpox, highlighting the virus's potential to emerge in previously controlled areas. Starting in 2022, clade II mpox circulated globally, especially among men who have sex with men (MSM), peaking in mid-2022 before declining to persistently lower levels by early 2023. Although clade II mpox typically exhibits a low case-fatality ratio (<1%), clade I has historically been associated with more severe disease and higher mortality. In 2023, the number of reported mpox cases continued to climb in the DRC, prompting the World Health Organization (WHO) to declare a Public Health Emergency of International Concern (PHEIC) in August 2024.
Recent surveillance indicates that sub-clade Ia MPXV is spreading in western DRC through multiple transmission modes, including contact with infected wild animals, household exposure, or sexual contact. By contrast, sub-clade Ib mpox in the eastern part of the country appears initially to spread via intimate or sexual contact between adults, followed by household transmission. Numerous environmental and social risk factors-including the consumption of rodent species, deforestation, climate change, civil unrest, population displacement, emerging MPXV variants, and weakened immunity-may be driving mpox incidence. Clade Ia mpox is currently affecting western parts of the DRC, yet the epidemiology remains poorly understood due to the limited number of laboratory-confirmed cases.
This study aims to characterize the clinical features of the 2024 mpox outbreak in Equateur Province of DRC and to identify associated risk factors. The findings will advance understanding of mpox transmission dynamics and disease severity, ultimately informing more effective prevention and control strategies in endemic settings.
The overall aim of this study is to describe the clinical characteristics of the 2024 mpox outbreak in the DRC and to identify associated risk factors. This research comprises three components: 1) a case-control study, 2) a transmission study, and 3) a vaccine effectiveness study.
And this protocol is for 3) a vaccine effectiveness study aim to evaluate the effectiveness of smallpox vaccination administered before the global eradication of smallpox against currently circulating mpox.
- Conditions
- Mpox (Monkeypox)
- Keywords
- vaccine efficacy, test negative control
- 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 |
|---|---|---|
| cases | • Cases are defined as Individuals who reported to local health agents with symptoms consistent with mpox and subsequently tested positive for mpox through a molecular-based diagnostic test. | |
| controls | Controls are defined as Individuals who reported to local health agents with symptoms consistent with mpox but subsequently tested negative for mpox through a molecular-based diagnostic test. |
What is being measured
The primary outcome is the main question the study is designed to answer.
Confirmed mpox
Definition: the positivity of mpox is determined based on the gene amplification testing for mpox genes.
The subjects sampled as suspected mpox patients will be classified based on pathogen diagnostic results: those testing positive will be defined as cases, and those testing negative will be defined as controls.
Measured: Day 1
Secondary outcomes (1)
Severity
Mpox severity will be evaluated based on skin lesion burden, clinical complications, organ dysfunction, and mortality outcomes.
Scoring Criteria:
Mild: Fewer than 25 lesions. Moderate: 26-99 lesions. Severe: 100 or more lesions or the presence of organ dysfunction, regardless of lesion count.
Fatal Outcome: If a patient dies from mpox or its complications during the study, the case will be classified as "fatal outcome." Assessment: The severity score will integrate the number of skin lesions across various anatomical sites and documented signs of complications (e.g., respiratory distress, neurological symptoms, renal impairment).
Measured: Day 1
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted22 May 2025
- Study start31 Jul 2025 (estimated)
- Primary completion31 Jul 2025 (estimated)
- Study completion31 Jul 2025 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Mpox (Monkeypox)Studies 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
- Case-control
- Time perspective
- Prospective
- Enrolment
- 144 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Osaka Metropolitan University
- Sponsor type
- University, hospital or other
- Collaborators
- Institut National de Recherche Biomedicale (INRB)
- Responsible party
- Principal investigator, Natsuko Kaku, Osaka Metropolitan University
- Investigators
- Natsuko Kaku, PhD, Principal investigator, Osaka Metropolitan University
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06984705
- Sponsor's protocol ID
- N553/BN/PMMF/2024-3
- Status last verified
- May 2025
- First submitted
- 14 May 2025
- Last updated
- 29 May 2025
- Results posted
- No
- Data monitoring committee
- No
- 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 29 May 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Epidemiological and Clinical Characteristics of Human Mpox Outbreak in Equateur Province in the Democratic Republic of Congo (Part3)
- ClinicalTrials.gov ID
- NCT06984705
- Acronym / sponsor ID
- N553/BN/PMMF/2024-3
- Conditions
- Mpox (Monkeypox)
- Keywords
- vaccine efficacy, test negative control
- Study type
- Observational
- Recruitment status
- Enrolling by invitation
- Enrolment
- 144 participants (estimated)
- Lead sponsor
- Osaka Metropolitan UniversityUniversity, hospital or other
- Collaborators
- Institut National de Recherche Biomedicale (INRB)
- Study start
- 31 Jul 2025 (estimated)
- Primary completion
- 31 Jul 2025 (estimated)
- Study completion
- 31 Jul 2025 (estimated)
- First posted
- 22 May 2025 (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 study is to evaluate the effectiveness of smallpox vaccination administered before the global eradication of smallpox against currently circulating mpox in the Democratic Republic of the Congo.
The main question it aims to answer is:
Is the smallpox vaccine experience protective against mpox infection ?
Researchers will compare mpox test positive group and negative group to see if the smallpox vaccine can protect against mpox infection.
Participants will
- be included after informed consent,
- respond the survey with structured questionnaire
- and accept skin lesion and blood sampling.
Detailed description
Mpox is caused by the monkeypox virus (MPXV), a member of the genus Orthopoxvirus (family Poxviridae). This virus is closely related to the variola virus, which causes smallpox. MPXV was first identified in 1958, and the first human case was reported in Democratic Republic of the Congo (DRC) in 1970. It was presumed that the smallpox vaccine would confer cross-protection against mpox. Following the global eradication of smallpox in 1980, mpox remained largely confined to limited regions in Central Africa-where zoonotic spillover from wild animal reservoirs constituted the primary route of transmission. Equateur Province is among the areas in the DRC with a notably high burden of reported mpox cases.
Over the past five decades, routine smallpox vaccination ceased worldwide, resulting in waning herd immunity against orthopoxviruses. During this period, mpox incidence rose markedly, with an estimated tenfold increase in global cases. Two principal genetic clades of MPXV have been identified: clade I (historically referred to as the Congo Basin clade) and clade II (the West African clade). In 2018, Nigeria experienced a resurgence of mpox, highlighting the virus's potential to emerge in previously controlled areas. Starting in 2022, clade II mpox circulated globally, especially among men who have sex with men (MSM), peaking in mid-2022 before declining to persistently lower levels by early 2023. Although clade II mpox typically exhibits a low case-fatality ratio (<1%), clade I has historically been associated with more severe disease and higher mortality. In 2023, the number of reported mpox cases continued to climb in the DRC, prompting the World Health Organization (WHO) to declare a Public Health Emergency of International Concern (PHEIC) in August 2024.
Recent surveillance indicates that sub-clade Ia MPXV is spreading in western DRC through multiple transmission modes, including contact with infected wild animals, household exposure, or sexual contact. By contrast, sub-clade Ib mpox in the eastern part of the country appears initially to spread via intimate or sexual contact between adults, followed by household transmission. Numerous environmental and social risk factors-including the consumption of rodent species, deforestation, climate change, civil unrest, population displacement, emerging MPXV variants, and weakened immunity-may be driving mpox incidence. Clade Ia mpox is currently affecting western parts of the DRC, yet the epidemiology remains poorly understood due to the limited number of laboratory-confirmed cases.
This study aims to characterize the clinical features of the 2024 mpox outbreak in Equateur Province of DRC and to identify associated risk factors. The findings will advance understanding of mpox transmission dynamics and disease severity, ultimately informing more effective prevention and control strategies in endemic settings.
The overall aim of this study is to describe the clinical characteristics of the 2024 mpox outbreak in the DRC and to identify associated risk factors. This research comprises three components: 1) a case-control study, 2) a transmission study, and 3) a vaccine effectiveness study.
And this protocol is for 3) a vaccine effectiveness study aim to evaluate the effectiveness of smallpox vaccination administered before the global eradication of smallpox against currently circulating mpox.
Study design
- Observational model
- Case-control
- Time perspective
- Prospective
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| cases | – | –• Cases are defined as Individuals who reported to local health agents with symptoms consistent with mpox and subsequently tested positive for mpox through a molecular-based diagnostic test. |
| controls | – | –Controls are defined as Individuals who reported to local health agents with symptoms consistent with mpox but subsequently tested negative for mpox through a molecular-based diagnostic test. |
Who may qualify
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Child, Adult, Older adult
- Study population
- This study targets patients born before 1984 with mpox-like skin lesions (both sexes) in the selected sites. All patients suspected of having mpox-like lesions and who provide proxy-assisted written informed consent to participate in the study are eligible for inclusion due to reduction of the risk of contact transmission with verbal agreement documented and confirmed by a witness. This approach prioritizes participant and staff safety while adhering to ethical standards.
Key inclusion criteria (4 listed)
- Individuals born before 1984: Although it is officially stated that smallpox vaccination was administered in the DRC until 1982, individuals born up to 1984 were included to account for potential discrepancies of several years in remote areas.
- Presence of skin lesions suspected to be mpox.
- Provision of informed consent:
- Proxy-assisted informed consent is allowed under safety considerations. Following oral consent, the investigator will document this on the informed consent form as a witness.
Key exclusion criteria (2 listed)
- Refusal to participate in the study: Individuals who decline to provide consent for study participation will be excluded.
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
Confirmed mpox
Time frame: Day 1
Definition: the positivity of mpox is determined based on the gene amplification testing for mpox genes. The subjects sampled as suspected mpox patients will be classified based on pathogen diagnostic results: those testing positive will be defined as cases, and those testing negative will be defined as controls.
1 secondary outcome
Severity
Time frame: Day 1
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 29 May 2025.
- Individual participant dataSharing planned: Undecided
Related trials for Mpox (Monkeypox)
RecruitingObservational study
Evaluation of Effectiveness and Safety of LC16m8 Mpox Vaccine in the Democratic Republic of Congo (DRC)
Mpox (Monkeypox), Mpox
Enrolling by invitationObservational study
New York City Observational Study of Mpox Immunity
Monkeypox, Mpox
Enrolling by invitation
Smart Analysis and Decision-Making for Emerging Infectious Diseases
Emerging Infectious Diseases, COVID-19
Active, not recruitingPhase 4
Smallpox Vaccine for Mpox Post-Exposure Prophylaxis: A Cluster RCT
Monkeypox
RecruitingPhase 2
A Randomized Clinical Trial Investigating the Safety, Reactogenicity, and Immunogenicity After Immunization With an mRNA-based Mpox Vaccine Candidate in Africa
Mpox (Monkeypox), Smallpox
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.
Natsuko Kaku, PhD principal investigator
Osaka Metropolitan University
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 Mpox (Monkeypox), run by Osaka Metropolitan University at 1 site in Democratic Republic of the Congo.
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 4 inclusion and 2 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: enrolling by invitation, as of the sponsor's last update on 29 May 2025. 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 Democratic Republic of the Congo. 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?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Confirmed mpox (time frame: Day 1). 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 29 May 2025.