Evaluation of Effectiveness and Safety of LC16m8 Mpox Vaccine in the Democratic Republic of Congo (DRC)

NCT07093489 | Not Yet Recruiting DMC

• 1 other identifier: MPX-001
• Study Type: observational
• Target: 11,990
• Locations: 1 country
• Sites: 1

Brief Summary

This is a health facility-based prospective test-negative (TND) case-control study to evaluate vaccine effectiveness and active safety monitoring (cohort event monitoring), and passive surveillance for evaluation of the safety of the LC16m8 mpox vaccine in individuals aged one year and older in the DRC. This study aims to assess the LC16m8 vaccine effectiveness and safety. The following activities will be carried out:

• Community engagement
• Enhanced health facility-based mpox disease surveillance
• Vaccination using the LC16m8 vaccine
• Safety monitoring following immunization
• LC16m8 Vaccine effectiveness evaluation using a TND Study Hypothesis: The LC16m8 vaccine, administered as pre-exposure prophylaxis, confers greater than 70% protection against symptomatic mpox disease among adults and children in the DRC.

Conditions

Mpox (Monkeypox); Mpox

Keywords

LC16m8; Mpox; Effectiveness; Safety; DRC

Outcome Measures

Primary Outcomes (1)

• Proportion of participants with complete mpox vaccination among those with symptomatic, RT-PCR confirmed mpox infection compared to those who test negative for mpox RT-PCR.

  This outcome measures the percentage of participants who had complete vaccination among those who tested positive for mpox by RT-PCR in comparison to the percentage of participants who had complete vaccination who tested negative for mpox by RT-PCR. Unit of Measure: Odds ratio Measurement tool: The odds of complete Vaccination status determined through vaccination record or participant self-report (complete vaccination is defined as symptom onset ≥14 days after receiving mpox vaccine) among mpox positive cases (RT-PCR positive) compared to the odds of complete Vaccination status among controls (mpox RT-PCR negative).

  At baseline (Day 0)

Secondary Outcomes (5)

• The percentage of participants with complete vaccination in different age strata of participants with RT-PCR-confirmed mpox disease compared with the percentage of participants with complete vaccination in those without mpox disease.

  At baseline (Day 0)

• The percentage of participants with incomplete vaccination among participants with RT-PCR-confirmed mpox disease compared to the percentage of participants with incomplete vaccination among participants with negative mpox RT-PCR(overall&stratified by age

  At baseline (Day 0)

• The percentage of participants with complete vaccination in those with RT-PCR-confirmed severe mpox disease compared to the percentage of participants with complete vaccination in those without mpox (overall & stratified by age).

  From baseline (Day 0) to severe outcome (death or hospitalization, assessed up to Day 42)

• The percentage of participants with incomplete vaccination in those with RT-PCR-confirmed severe mpox disease compared to the percentage of incomplete vaccination among those without mpox disease (overall & stratified by age).

  From enrollment (Day 0) to severe outcome (death or hospitalization, assessed up to Day 42)

• Evaluate the incidence of serious adverse events (SAEs) and adverse event of special interest (AESI) of the LC16m8 vaccine using a cohort event monitoring (CEM) in a defined cohort and passive surveillance in all vaccinees.

  Within 12 weeks following immunization in the CEM cohort and with 12 months in the rest of the vaccinees (not part of the CEM cohort)

Study Arms (2)

Cohort Event Monitoring (CEM) - Safety cohort

At enrollment/vaccination visit, participants will be consecutively invited to be enrolled in the safety subset until the sample size of 10,000 has been achieved. The enrollment aims to include a proportional number of participants from various age groups, including 1-5 years, 6-12 years and 13-18 years, with representation from both sexes. The participation will be strictly voluntary according to the eligibility criteria. Enrolled vaccinees will be actively followed up through phone calls/home visits/Health facility visits for the SAEs and AESIs assessment at weekly intervals for the first month and then at monthly intervals until 12 weeks post vaccination. Vaccinees/parents/guardians will be advised to return to the sentinel health facility if any serious event occurs at any time.

Biological: LC16m8

Vaccine Effectiveness (VE) Assessment

Health facility-based enhanced mpox surveillance will be implemented to record mpox cases within the vaccination catchment area. The study will be done in 2 or more health zones identified as hot spots by the DRC government. All patients presenting with probable or suspected mpox to the surveillance healthcare facilities will be approached for testing and enrollment into the surveillance study. Vaccine effectiveness will be estimated using cases and controls assembled based on specific inclusion/exclusion criteria. A total of 1,990 participants (398 cases and 1,592 controls) will be required for assessment of vaccine effectiveness.

Interventions

LC16m8 BIOLOGICAL

LC16m8 vaccine will be offered to all individuals aged \>1 year and meet the inclusion criteria within the catchment population. This will be done in line with the DRC government's LC16m8 vaccine roll out plan.

Cohort Event Monitoring (CEM) - Safety cohort

Eligibility Criteria

• Age: 1 Year+
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Child (0-17), Adult (18-64), Older Adult (65+)
• Sampling Method: Non-Probability Sample

Study Population

The vaccination will be conducted in 2 to 3 selected health zones/areas which meet the criteria for a hotspot as defined by the DRC vaccination strategy for targeted vaccine delivery. As of February 2025, the DRC government has updated their comprehensive mpox vaccination plan which targets both high-risk groups (e.g., healthcare workers, contacts of confirmed cases, etc.) as well as population residing in 57 health zones considered mpox hotspots based on recent epidemiologic data. Selection of health zones/area for the study, where LC16m8 is expected to be offered to everyone one year or older, will be determined based on the latest mpox epidemiological data, operational feasibility, and existing research infrastructure in close consultation with DRC MoH, Institut National de Santé Publique (INSP), and local stakeholders.

You may qualify if:

• Individuals aged 12 months and above
• Living in the study catchment area
• Written informed consent/assent (if applicable)

You may not qualify if:

• Prior receipt of any mpox vaccine dose
• Women known to be pregnant or breast feeding
• Individuals suffering from any spreading skin disease
• Immunocompromised individuals with known severe immuno-deficiency conditions (example, HIVAIDS, individuals being on chronic use of systemic steroids (\>2 mg/kg/day or \>20 mg/day prednisolone equivalent for periods exceeding 10 days, cytotoxic or other immunosuppressive drugs)
• Individuals with known underlying uncontrolled chronic diseases such as diabetes mellitus, cardiovascular disease, renal disease, hepatic disease, hematological disease, and developmental disturbance
• Individuals with a history of hypersensitivity caused by a component of the vaccine
• Individuals with objective fever (Frontal temperature ≥ 38.5°C) or axillary temperature \> 37.5 °C
• Individuals suffering from acute illness within 48 hours prior to vaccination and based on investigator judgement.
• Receipt of any live vaccine injection within the previous 27 days (measles vaccine, rubella vaccine, mumps vaccine, varicella vaccine, BCG vaccine, yellow fever vaccine...).
• Cohort Event Monitoring (CEM):
• Written informed consent
• Individual who receives single dose of LC16m8 vaccine at one of the vaccination centers participating in the study.
• Must be reachable by phone (must have an active phone number of his/her own or in the household) throughout study participation.
• Individual/parent/guardian unable to comply with the study procedures
• Mpox surveillance (VE):

Sponsors & Collaborators

• International Vaccine Institute: lead
• Japan Institute for Health Security (JIHS): collaborator
• Institut National de Recherche Biomédicale. Kinshasa, République Démocratique du Congo: collaborator

Study Sites (1)

The Institut National de la Recherche Biomédicale (INRB)

Kinshasa, Democratic Republic of the Congo

Location

Biospecimen

Retention: SAMPLES WITH DNA

Skin swabs will be collected from all patients presenting with skin lesions suggestive of mpox. Oro-pharyngeal swabs and saliva will be collected from one hundred Consecutively invited patients with skin lesions to assess the diagnostic accuracy of other samples compared to skin swab. In patients without skin lesions, oro-pharyngeal swab will be collected. Skin lesion material includes swabs of lesion surface and/or exudate, or lesion crusts. Lesions will be swabbed vigorously to ensure adequate viral DNA is collected.

MeSH Terms

Conditions

Mpox, Monkeypox

Interventions

smallpox vaccine LC16m8

Condition Hierarchy (Ancestors)

Poxviridae Infections; DNA Virus Infections; Virus Diseases; Infections; Primate Diseases; Animal Diseases; Rodent Diseases

Study Officials

• Jean Jacques Muyembe

  Institut National de la Recherche Biomédicale

  PRINCIPAL INVESTIGATOR

• Norio Ohmagari

  Japan Institute for Health Security

  PRINCIPAL INVESTIGATOR

• Florian Marks

  International Vaccine Institute

  STUDY CHAIR

Central Study Contacts

Birkneh Tilahun Tadesse, MD

CONTACT

+821098041348; birkneh.tadesse@ivi.int

Meseret Behute, MD

CONTACT

+82129732401; Meseret.Behute@ivi.int

Study Design

• Study Type: observational
• Observational Model: OTHER
• Time Perspective: PROSPECTIVE
• Target Duration: 12 Weeks
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: July 7, 2025
• First Posted: July 30, 2025
• Study Start: September 30, 2025
• Primary Completion (Estimated): August 1, 2027
• Study Completion (Estimated): December 31, 2027
• Last Updated: September 15, 2025

Record last verified: 2025-09

Data Sharing

• IPD Sharing: Will not share

Locations

DE (1)