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MonkeypoxPhase 3MPOX-COLNCT06223919

Efficacy/Effectiveness, Safety, and Immunogenicity of LC16m8 Mpox Vaccine in Colombia

A Phase 3 study testing LC16m8 in people with Monkeypox, run by Universidad Nacional de Colombia at 3 sites in Colombia.

Active, not recruiting

Under way, not looking for participants. Everyone needed has enrolled. The study is still running.

Official record
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Trial summary

Background: Mpox is a zoonotic disease caused by the mpox virus (MPXV). It has been endemic in West and Central African countries. However, the soaring number of those has been reported in non-endemic countries since May 2022, making World Health Organization (WHO) declare a global mpox Public Health Emergency of… Read more about this study

Who is it for?
Ages 18 to 50 yearsHealthy volunteers can take part
Conditions the study is for
Monkeypox
What is being tested?
LC16m8
Could I receive a placebo?
No, everyone receives an active treatment
How many people
8,686 participants
Where
3 sitesColombia
Study dates
16 Dec 2023to Dec 2025
Phase
Phase 3
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 18 to 50 years
  • All sexes
  • Healthy volunteers accepted
  • Adult
  1. Inclusion Criteria:
  2. Sex: Males and females
  3. Age: ≥18 and ≤ 50 years old
  4. Persons must be willing and sign the Informed Consent (I.C.).
  5. Any of the following conditions including clinical conditions /manifestation:
  • People living with the HIV, with stable infection determined by participant´s being on antiretroviral therapy with a blood CD4+ cell count, ≥ 200 cells/mm3 in the last six months before study enrolment
  1. Persons that use PrEP (HIV Pre-exposure prophylaxis).
  2. Homosexual, Bisexual, or other men who have sex with men (MSM) with multiple sexual partners. Commercial sex workers (CSW) and partners CSW
  3. A female participant is eligible to participate if the participant meets one of the inclusion criteria numbered -1, -2 or -3 above. The participant cannot be pregnant or lactating. Additionally, the female participant must meet one of the following conditions:
  • The participant has non-childbearing potential. To be considered of non-childbearing potential, a female must be post-menopausal for at least one year or surgically sterile. OR
  • The participant has a childbearing potential and agrees to use an effective contraceptive method or abstinence from at least 4 weeks before the vaccine administration until at least 2 months after the administration and have a negative highly sensitive pregnancy test (urine or serum as required by local regulation) within 10 days before vaccination.
  1. Exclusion Criteria:
  2. Subjects with an unstable medical condition as determined by their initial medical history, physical examination, or laboratory results
  3. Subjects with a terminal disease.
  4. Subjects with a medical record of anaphylaxis caused by any of the vaccine's excipients or with previous undesired reactions to other vaccines such us (Allergic reactions, Guillain barre syndrome, Varicella zoster, or shingles).
  5. Previous medical record of Mpox.
  6. Subjects living with HIV with a CD4+ T cell count of fewer than 200 cells/mm3.
  7. Pregnant or breastfeeding woman.
  8. Active or medical record of atopic dermatitis or eczema, or with close contact with someone with an active or medical record of atopic dermatitis or eczema.
  9. The presence of a skin condition with extensive breaks in the skin, such as burns, impetigo, contact dermatitis, or zoster (shingles), is not likely to heal by the day of vaccination.
  10. Using immunosuppressive medications, in eye drops, by mouth, or topically (nasal sprays and inhaled corticosteroids are permissible).
  11. Active or past malignancy except for cutaneous basal or squamous cell carcinomas.
  12. An Autoimmune disease.
  13. History of heart failure with decreased left ventricular ejection fraction (<40%).
  14. Medical record of splenectomy.
  15. Medical record of solid organ or bone marrow transplantation.
  16. Medical record of keloid scar development
  17. Psychiatric condition that precludes compliance with the protocol.
  18. People who received or plan to receive licensed live vaccines 30 days before or after study vaccination.
  19. People who received or planned to receive immunoglobulin or other blood products 60 days before HIV screening.
  20. People who received or plan to receive experimental drugs/vaccines 30 days before study vaccination or before study completion.
  21. People who received or planned to receive systemic immunosuppressive therapy and radiation therapy 30 days before or after the study vaccination.
  22. Use of systemic chemotherapy within five years before the study vaccination.
  23. Medical record of smallpox vaccination and/or evidence of scarring at the vaccination site.
  24. Allergies to streptomycin sulfate and/or erythromycin lactobionate.

Trial locations and contacts

3 sites in 1 country.

Colombia3 sites

  • Clinica Universitaria Colombia - Centro Medico Teusaquillo

    Bogotá, Bogota D.C.

  • Hospital Universitario San Ignacio

    Bogotá, Bogota D.C.

  • Infecto Clinicos

    Bogotá, Bogota D.C.

Other trials in Colombia

About this study

Official title: Randomized Trial to Evaluate the Efficacy/Effectiveness, Safety, and Immunogenicity of Replicative Live Attenuated Vaccinia Virus Vaccine LC16m8 for Prevention Against Mpox in High-risk Populations During Vaccination Deployment in Colombia

Background: Mpox is a zoonotic disease caused by the mpox virus (MPXV). It has been endemic in West and Central African countries. However, the soaring number of those has been reported in non-endemic countries since May 2022, making World Health Organization (WHO) declare a global mpox Public Health Emergency of International Concern in July 2022. Those with mpox are primarily young men (96%, and median age of 34 [interquartile range (IQR):29-41 years]), and 84% are self-identified homosexual, bisexual, and men who have sex with men (MSM) . Furthermore, about half of these mpox cases with known human immunodeficiency virus 1(HIV-1, hereafter shown as HIV). WHO recommended prioritizing vaccinating those populations as high-risk populations, including those with HIV, since they will be severely ill if infected mpox virus (MPXV). The smallpox vaccine is expected to offer cross-immunity against MPXV. Under these circumstances, WHO included LC16m8 in the recommended vaccine lists for mpox as the product is expected to have cross-efficacy and immunogenicity against MPXV. Additionally, the safety profile was demonstrated in both adults and children, including infants who have low immuno-functions. Given that Colombia has the fifth highest mpox prevalence worldwide, WHO encouraged the authorities to implement vaccine programs while evaluating the safety and efficacy of LC16m8 as collaborative research. Following WHO initiative, this study is being conducted with the collaboration of various experts from Colombia and Japan on a large scale, with vaccine contributions and funding from Japan and Colombia However, the current infection situation differs from six months ago, and there have been few recent cases of MPXV infection in the country.

Primary objective: To determine the efficacy of the replicating attenuated live vaccinia virus vaccine LC16m8 against laboratory-confirmed mpox and safety in a Colombian population with a high risk of being infected with MPXV(See the Inclusion Criteria), by comparing the immediate vaccination group and the delayed vaccination groups to assess safety and tolerability until 180 days after vaccination. Study design: An open randomized deployment study (1:1 Immediate and Delayed vaccination group).

Study population: People at high risk of serious illness if infected with MPXV and those who engage in risk behaviors for acquiring MPXV infection.

Read the detailed description

Hypothesis: LC16m8 is a safe and effective vaccine for high-risk immunocompromised populations, including those living with HIV.

Intervention evaluation plan: Vaccinate with LC16m8 those people randomly assigned to two groups: immediate and deferred vaccination 1:1 with a follow-up period of 180 days to evaluate new cases infected by MPXV.

General design: This research is being carried out within the framework of the mpox vaccination implementation program in Colombia. It comprises the following three complementary components:

  • Study section 1: Parallel open sequential randomized controlled trial to evaluate the efficacy of LC16m8 vaccine in preventing MPXV infection.
  • Study section 2: Cohort study based on the same population base
  • Study section 3: Cohort study compared to real world cohort

STUDY SECTION 1: Participants will receive LC16m8 vaccine within 6 weeks (immediate vaccination) or 6 weeks later (delayed vaccination) after randomization. Both groups will be followed up at 14, 30 and 180 days after vaccination, mainly through phone calls.

The study will compare the incidence of new MPXV infections in the early vaccination group from day 14 to day 42 after vaccination with the incidence of rate at which new MPXV infections occur in the delayed vaccination group from 42 days before to 14 days after vaccination; this comparison will be made from the hazard ratio or proportional hazard model.

Additionally, the immune response, including neutralizing antibody titers, will be evaluated from the day of vaccination (Day 1) to 180 days post-vaccination in 60 participants, who will be selected from a single research center and only belonging to the immediate vaccination group. Two 5 mL blood samples (converted to serum) will be collected from the participants for immunogenicity assessments at the following time points: Days 0, 14 (+/-2), 30 (+/-2), and 180 (+/-7) post-vaccination. Another blood sample for immunogenicity assessment will be collected before the vaccine is administered on Day 0.

Safety events will be intensively sought, especially in the first 14 days after vaccine administration and all those arising within 180 days post-vaccination. Participants will also self-report symptoms through a mobile application designed for this purpose.

STUDY SECTION 2 AND 3 (NESTED STUDIES)

  • Study of cohorts supported on the same population base: A total of 1,000 vaccinated individuals, including participants in section 1 of the study, will make up the exposed group. The unexposed group will consist of 4,000 unvaccinated individuals from the same population base (a list of HIV patients with a CD4 count greater than 200 cells/ml and PrEP users). who are patients with HIV and CD4 greater than 200 cells/mm3, and PrEP users. The group of unvaccinated individuals are people who meet the study's criteria but did not agree to be vaccinated or withdrew their consent. We will compare the cumulative incidence of these two groups over a 180-day period. We will obtain information about non-participants and withdrawals from the records at the INS and local health entities. We will use the hazard ratio (HR) to compare these groups, and we will also conduct a propensity score analysis.The objective is to demonstrate the effectiveness and safety of the LC16m8 replicating vaccine against laboratory-confirmed MPXV in a Colombian population at high risk of MPXV infection (see inclusion criteria).

Assumptions:

  • A relative risk reduction (RRR) of 75% is assumed to calculate the sample size.
  • Confidence level: 95%
  • Ratio of vaccinated:unvaccinated: 1:4
  • RRR: Risk (Rx) in the unvaccinated group - Rx in the vaccinated group/(Rx) in the unvaccinated group.

The incidence of the event (Mpox case) is considered to be 0.4% per period in the exposed group (I Exp (+)) and 1.6% per period in the unexposed group (I exp (-)), in accordance with the current situation of Mpox infection in Colombia.

Incidence in vaccinated 4/1000 = 0.004 Incidence in unvaccinated 64/4000 = 0.016 RR = 0.2756 (95% CI: 0.1057 ; 0.7185) Relative risk (RR): Risk (Rx) in unvaccinated/Rx in vaccinated RAR***: -1.2888 (95% CI: -2.247; - 0.3306) RRR= 0.7244 (95% CI: 0.2815; 0.8943) Power: 0.92 where RR is relative risk, RAR is absolute risk reduction and RRR is relative risk reduction.

The Ho could be rejected.

  • Cohort study compared to the real-world cohort: There will be no sample size because all the information from the databases will be used in the cohort, so a sample is not necessary since we will take all the subjects in HIV and PrEP programs.
Conditions
Monkeypox
Being tested
LC16m8
Keywords
Vaccines, monkeypox, Mpox, Mpox virus
Medical subject headings
Mpox, Monkeypox

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

  • LC16m8Biological

    LC16m8 should be stored at temperatures between -35°C and -20°C. The product should not be stored at temperatures below -35°C, because deterioration or damage of the rubber stopper could occur.

    The virus in this product is sensitive to sunlight and is quickly inactivated, so care should be taken to avoid exposure to light, both before or after reconstitution.

    Carefully examine the content at the time of reconstitution. Do not use if precipitation, contamination of foreign substances, or other abnormalities are observed.

    This product should be dissolving the drug immediately before inoculation. Once dissolved, it should be used immediately. Since this product does not contain thimerosal, once the stopper is removed, any solution remained in the vial must be disposed of.

    Do not restore or reuse the remaining solution. Shelf Life: 10 years from the date of passing the national test for lot-release Bottle containing about 250 doses

Study groups in NCT06223919
Study groupRoleWhat they receive
Immediate vaccinationExperimentalThis vaccin is a yellowish-yellow dry preparation containing live vaccinia virus (strain LC16m8). When the accompanying solvent is added, it dissolves rapidly to form a clear or slightly cloudy yellowish-red or reddish liquid. The ingredients of this vaccin are contained in 0.5 mL of a solution of this product dissolved in 0.5 mL of the accompanying solvent (20 vol% glycerin-added water for injection). Just one dose of vaccine will be administered according to standardized operating procedure (SOP). Briefly, the vaccine is dissolved with 0.5 mL of a diluent provided. The reconstituted vaccine is usually administered percutaneously at a dose of approximately 0.025 mL by the multiple puncture technique using a bifurcated needle. The number of punctures will be 15 times. Procedures for vaccine administration are described in detail in the SOP. The participant must be observed at the vaccination site for 30 minutes after vaccine administration to observe possible immediate reactions.
Receives: Biological: LC16m8
Delayed vaccinationActive comparatorThe use of placebo as a control group is essential to scientifically assess the efficacy of vaccines in clinical trials and to obtain reliable evidence in preventing the onset of disease. However, the use of a placebo is unethical. Subjects are at high risk of mpox and must not be given a placebo. Therefore, a design was applied in which the immediate treatment group was evaluated with the delayed group as a control group. A period of six weeks was set aside between the immediate and delayed treatment groups to be used for logistics, such as preparations and delivery of the vaccine in the delayed treatment group. It is ethical, for the same reason, because it prevents inequities based on the abovementioned reasons.
Receives: Biological: LC16m8

What is being measured

The primary outcome is the main question the study is designed to answer.

  1. Incidence rate of mpox infection between the immediate versus delayed vaccination groups from day 15 to day 56 post-vaccination of the immediate group.

    The incidence rate of new cases of mpox (laboratory-confirmed) will be calculated with a 95% confidence interval (CI) based on the Poisson distribution for each vaccination group. The time to the onset of the first occurrence of a confirmed mpox case in the subject will be summarized graphically using the Kaplan-Meier method.

    Measured: For immediate vaccination group: from days 15th to 56th post vaccination. For delayed vaccination group: from enrollment to the day of vaccination (42 days later)

  2. Incidence of adverse events between the vaccination groups

    Proportion of adverse events (serious and non-serious) presented in participants included in the two vaccination groups (immediate and delayed)

    Measured: up to 6 months post vaccination

  3. Incidence rate of mpox infection between the vaccinated cohort versus the unvaccinated cohort

    The incidence rate of new cases of mpox (laboratory-confirmed) will be calculated with a 95% confidence interval (CI) based on the Poisson distribution for each cohort. The time to the onset of the first occurrence of a confirmed mpox case in the subject will be summarized graphically using the Kaplan-Meier method.

    Measured: 6 months post vaccination

Secondary outcomes (6)

  1. Frequency of laboratory-confirmed severe cases of MPOX in the immediate and delayed vaccination groups.

    Proportion of participants with confirmed MPOX that presented severe symptoms requiring hospitalization, emergency department care, or death associated with MPOX.

    Measured: 6 months post-vaccination

  2. Incidence rate of mpox suspected cases without laboratory confirmation between the immediate versus delayed vaccination groups from day 15 to day 56 post-vaccination of the immediate group.

    Mpox suspected cases correspond to participants that present with skin lesions to the emergency room or treating patient.

    Measured: - For immediate vaccination group: from days 15th to 56th post vaccination. For delayed vaccination group: from enrollment to the day of vaccination (42 days later

  3. Proportion of patients with seroconversion of geometric mean neutralizing titer (GMT) of LC16m8.

    Seroconversion is considered in cases where the titer on day 30 is 4 times higher than on day 0.

    Measured: up to 6 months post vaccination

  4. Geometric mean of LC16m8 neutralizing titer by vaccination group.

    overall geometric mean of each group (immediate and delayed vaccination)

    Measured: up to 6 months post vaccination

  5. Geometric mean of LC16m8 neutralizing titer by helper T lymphocytes (CD4) count in each vaccination group

    Subgroups of patients with a CD4 count of 350 or less and those with a CD4 count greater than 350 will be compared for each vaccination group.

    Measured: up to 6 months post vaccination

  6. Maximum lesion area (MLA) in mm² after scarification with vaccination LC16m8

    take area measured 14 days post vaccination

    Measured: up to 6 months post vaccination

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted25 Jan 2024
  2. Study start16 Dec 2023
  3. Primary completion20 Aug 2024
  4. Study completionDec 2025 (estimated)

Resources

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design
Study type
Interventional
Phase
Phase 3
Primary purpose
Prevention
Allocation
Randomised
Intervention model
Parallel groups
Model description
Vaccinate LC16m8 randomly assigned to two groups consisting of two groups of Immediate and Delayed vaccination 1:1 with a follow-up period of 180 days to evaluate newly MPXV-infected cases as well as immuno-responses including neutralizing antibody titers.
Masking
None (open label)
Enrolment
8,686 participants (estimated)
IDs, dates and publications
ClinicalTrials.gov ID
NCT06223919
Sponsor's protocol ID
PI-UN-1760
Acronym
MPOX-COL
Status last verified
Aug 2025
First submitted
28 Dec 2023
Last updated
4 Sep 2025
Results posted
No
Data monitoring committee
Yes
FDA-regulated drug
No
FDA-regulated device
No
Individual data sharing
No

Publications

  • Adnan N, Haq ZU, Malik A, Mehmood A, Ishaq U, Faraz M, Malik J, Mehmoodi A. Human monkeypox virus: An updated review. Medicine (Baltimore). 2022 Sep 2;101(35):e30406. doi: 10.1097/MD.0000000000030406.

    PubMed 36107544

  • Karagoz A, Tombuloglu H, Alsaeed M, Tombuloglu G, AlRubaish AA, Mahmoud A, Smajlovic S, Cordic S, Rabaan AA, Alsuhaimi E. Monkeypox (mpox) virus: Classification, origin, transmission, genome organization, antiviral drugs, and molecular diagnosis. J Infect Public Health. 2023 Apr;16(4):531-541. doi: 10.1016/j.jiph.2023.02.003. Epub 2023 Feb 9.

    PubMed 36801633

  • Mitja O, Ogoina D, Titanji BK, Galvan C, Muyembe JJ, Marks M, Orkin CM. Monkeypox. Lancet. 2023 Jan 7;401(10370):60-74. doi: 10.1016/S0140-6736(22)02075-X. Epub 2022 Nov 17.

    PubMed 36403582

  • Di Giulio DB, Eckburg PB. Human monkeypox: an emerging zoonosis. Lancet Infect Dis. 2004 Jan;4(1):15-25. doi: 10.1016/s1473-3099(03)00856-9.

    PubMed 14720564

  • Shchelkunov SN, Marennikova SS, Moyer RW. Orthopoxviruses pathogenic for humans: Springer Science & Business Media; 2006.

  • McInnes et al. Family: Poxviridae [Website]. International Committee on Taxonomy of Viruses (ICTV); 2023 [updated 2023/04/17.

  • Parker S, Buller RM. A review of experimental and natural infections of animals with monkeypox virus between 1958 and 2012. Future Virol. 2013 Feb 1;8(2):129-157. doi: 10.2217/fvl.12.130.

    PubMed 23626656

  • Magnus Pv, Andersen EK, Petersen KB, Birch-Andersen A. A POX-LIKE DISEASE IN CYNOMOLGUS MONKEYS. Acta Pathologica Microbiologica Scandinavica. 1959;46(2):156-76.

  • Kozlov M. Monkeypox in Africa: the science the world ignored. Nature. 2022 Jul;607(7917):17-18. doi: 10.1038/d41586-022-01686-z. No abstract available.

    PubMed 35739391

  • Tomori O, Blumberg L. Response to the multi-country monkeypox outbreak: a view from Africa. J Travel Med. 2022 Dec 27;29(8):taac138. doi: 10.1093/jtm/taac138. No abstract available.

    PubMed 36440640

  • Esposito JJ, Knight JC. Orthopoxvirus DNA: a comparison of restriction profiles and maps. Virology. 1985 May;143(1):230-51. doi: 10.1016/0042-6822(85)90111-4.

    PubMed 2998003

  • Likos AM, Sammons SA, Olson VA, Frace AM, Li Y, Olsen-Rasmussen M, Davidson W, Galloway R, Khristova ML, Reynolds MG, Zhao H, Carroll DS, Curns A, Formenty P, Esposito JJ, Regnery RL, Damon IK. A tale of two clades: monkeypox viruses. J Gen Virol. 2005 Oct;86(Pt 10):2661-2672. doi: 10.1099/vir.0.81215-0.

    PubMed 16186219

  • Bunge EM, Hoet B, Chen L, Lienert F, Weidenthaler H, Baer LR, Steffen R. The changing epidemiology of human monkeypox-A potential threat? A systematic review. PLoS Negl Trop Dis. 2022 Feb 11;16(2):e0010141. doi: 10.1371/journal.pntd.0010141. eCollection 2022 Feb.

    PubMed 35148313

  • Velavan TP, Meyer CG. Monkeypox 2022 outbreak: An update. Trop Med Int Health. 2022 Jul;27(7):604-605. doi: 10.1111/tmi.13785. Epub 2022 Jun 14. No abstract available.

    PubMed 35633308

  • Edouard Mathieu FS, Saloni Dattani, Hannah Ritchie and Max Roser -

Questions about this trial

What is this clinical trial studying?

A Phase 3 study testing LC16m8 in people with Monkeypox, run by Universidad Nacional de Colombia at 3 sites in Colombia.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

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: under way, not looking for participants, as of the sponsor's last update on 4 Sep 2025. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 3 sites in Colombia. 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.

What does this phase mean?

Phase 3 studies compare the treatment with the current standard treatment or a placebo in a large group, to confirm how well it works and watch for side effects.

Not every study follows the same path, and some studies (observational studies, device studies) have no phase.

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?

Incidence rate of mpox infection between the immediate versus delayed vaccination groups from day 15 to day 56 post-vaccination of the immediate group. (time frame: For immediate vaccination group: from days 15th to 56th post vaccination. For delayed vaccination group: from enrollment to the day of vaccination (42 days later)). The study lists 3 primary outcomes in all. It is what the study was designed to measure, not a finding.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT06223919, which also lists 67 linked publications.

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 4 Sep 2025.

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