NCT05745987

Brief Summary

A cluster randomized controlled trial to determine if smallpox vaccine reduces secondary cases and symptom severity in persons exposed to mpox.

Trial Health

80
On Track

Trial Health Score

Automated assessment based on enrollment pace, timeline, and geographic reach

Enrollment
3,000

participants targeted

Target at P75+ for phase_4

Timeline
8mo left

Started Sep 2024

Typical duration for phase_4

Geographic Reach
3 countries

10 active sites

Status
recruiting

Health score is calculated from publicly available data and should be used for screening purposes only.

Trial Relationships

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Study Timeline

Key milestones and dates

Study Progress72%
Sep 2024Dec 2026

First Submitted

Initial submission to the registry

February 10, 2023

Completed
17 days until next milestone

First Posted

Study publicly available on registry

February 27, 2023

Completed
1.6 years until next milestone

Study Start

First participant enrolled

September 17, 2024

Completed
1.7 years until next milestone

Primary Completion

Last participant's last visit for primary outcome

June 1, 2026

Expected
6 months until next milestone

Study Completion

Last participant's last visit for all outcomes

December 1, 2026

Last Updated

July 6, 2025

Status Verified

July 1, 2025

Enrollment Period

1.7 years

First QC Date

February 10, 2023

Last Update Submit

July 3, 2025

Conditions

Monkeypox

Keywords

mpox

Outcome Measures

Primary Outcomes (2)

  • PCR-confirmed Mpox

    To evaluate if smallpox vaccine vs control prevents RT-PCR confirmed mpox

    8 weeks

  • Symptom severity

    To evaluate if smallpox vaccine vs control affects symptom severity

    8 weeks

Secondary Outcomes (7)

  • Resolution of skin lesions

    8 weeks

  • Number of skin lesions

    8 weeks

  • Self-reported Quality of Life

    8 weeks

  • Mpox complications

    8 weeks

  • Mpox Pain

    8 weeks

  • +2 more secondary outcomes

Other Outcomes (1)

  • Safety (SAEs, AESI)

    6 months

Study Arms (2)

Smallpox vaccine

EXPERIMENTAL

Participants will receive the Bavarian Nordic smallpox vaccine 0.5 ml single-dose

Drug: Bavarian Nordic smallpox vaccine

Typhoid vaccine

ACTIVE COMPARATOR

Participants will receive the Typhim Vi® typhoid vaccine 0.5 ml single-dose

Drug: Typhoid VI Polysaccharide Vaccine Injectable Solution

Interventions

Bavarian Nordic smallpox vaccineDRUG

A single dose of the Bavarian Nordic smallpox vaccine will be given at baseline.

Also known as: Imvamune
Smallpox vaccine
Typhoid VI Polysaccharide Vaccine Injectable SolutionDRUG

A single dose of the typhoid vaccine will be given at baseline.

Typhoid vaccine

Eligibility Criteria

Age2 Years+
Sexall
Healthy VolunteersYes
Age GroupsChild (0-17), Adult (18-64), Older Adult (65+)

You may qualify if:

  • Household member of person with laboratory confirmed mpox
  • Age ≥ 2 years
  • Within 14 days of onset of illness in mpox index case

You may not qualify if:

  • Pregnancy
  • Breastfeeding
  • Past serious allergic reaction to study vaccine components
  • Previous smallpox vaccination
  • Current or planned use of another investigational drug at any point during study participation

Contact the study team to confirm eligibility.

Sponsors & Collaborators

Study Sites (10)

Catholic University of Bukavu

Kinshasa, Bukavu, Democratic Republic of the Congo

RECRUITING

Federal Medical Center

Abuja, Nigeria

NOT YET RECRUITING

University of Abuja Teaching Hospital

Abuja, Nigeria

NOT YET RECRUITING

University of Ibadan

Ibadan, Nigeria

NOT YET RECRUITING

Irrua Specialist Teaching Hospital

Irrua, Nigeria

NOT YET RECRUITING

Aminu Kano Teaching Hospital

Kano, Nigeria

NOT YET RECRUITING

Lagos University Teaching Hospital

Lagos, Nigeria

NOT YET RECRUITING

Niger Delta Teaching Hospital

Okolobiri, Nigeria

NOT YET RECRUITING

University of Port Harcourt Teaching Hospital

Port Harcourt, Nigeria

NOT YET RECRUITING

Makerere University Lung Institute

Kampala, Uganda

NOT YET RECRUITING

MeSH Terms

Conditions

Mpox, Monkeypox

Interventions

smallpox and monkeypox vaccine modified vaccinia ankara-bavarian nordic

Condition Hierarchy (Ancestors)

Poxviridae InfectionsDNA Virus InfectionsVirus DiseasesInfectionsPrimate DiseasesAnimal DiseasesRodent Diseases

Study Officials

  • Mark Loeb, MD

    McMaster University

    PRINCIPAL INVESTIGATOR

Central Study Contacts

Mark Loeb, MD

CONTACT

9055259140loebm@mcmaster.ca

Study Design

Study Type
interventional
Phase
phase 4
Allocation
RANDOMIZED
Masking
TRIPLE
Who Masked
PARTICIPANT, INVESTIGATOR, OUTCOMES ASSESSOR
Masking Details
Participants will not know which vaccine they receive until after the study is completed.
Purpose
PREVENTION
Intervention Model
PARALLEL
Model Details: Each group will be randomly selected to receive the smallpox vaccine or the typhoid vaccine
Sponsor Type
OTHER
Responsible Party
SPONSOR

Study Record Dates

First Submitted

February 10, 2023

First Posted

February 27, 2023

Study Start

September 17, 2024

Primary Completion (Estimated)

June 1, 2026

Study Completion (Estimated)

December 1, 2026

Last Updated

July 6, 2025

Record last verified: 2025-07

Data Sharing

IPD Sharing
Will not share

Locations

DE(1)NG(8)UG(1)