Smallpox Vaccine for Mpox Post-Exposure Prophylaxis: A Cluster RCT (SMART)

July 3, 2025 updated by: McMaster University

SMART (Smallpox Vaccine for Mpox Post-Exposure Prophylaxis: A Cluster Randomized Controlled Trial)

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

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Detailed Description

A pragmatic, adaptive, multi-site, cluster randomized trial where households with one or more persons confirmed to have mpox will be randomized to smallpox vaccine or control. The co-primary outcomes are RT-PCR confirmed mpox and symptom severity.

Study Type

Interventional

Enrollment (Estimated)

3000

Phase

  • Phase 4

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Locations

  • Congo, The Democratic Republic of the
    • Bukavu
      • Kinshasa, Bukavu, Congo, The Democratic Republic of the
        • Recruiting
        • Catholic University of Bukavu
        • Contact:
          • Patrick Katoto, MD
        • Contact:
          • Esto Bahizire, MD
  • Nigeria
      • Abuja, Nigeria
        • Not yet recruiting
        • University of Abuja Teaching Hospital
        • Contact:
          • Zaiyad Garba, MD
      • Abuja, Nigeria
        • Not yet recruiting
        • Federal Medical Center
        • Contact:
          • Haroun Adamu, MD
      • Ibadan, Nigeria
        • Not yet recruiting
        • University of Ibadan
        • Contact:
          • Olukemi Adekanmbi, MD
      • Irrua, Nigeria
        • Not yet recruiting
        • Irrua Specialist Teaching Hospital
        • Contact:
          • Sebastine Oiwoh, MD
      • Kano, Nigeria
        • Not yet recruiting
        • Aminu Kano Teaching Hospital
        • Contact:
          • Garba Ilyasu, MD
      • Lagos, Nigeria
        • Not yet recruiting
        • Lagos University Teaching Hospital
        • Contact:
          • Iorhen Ephraim, MD
      • Okolobiri, Nigeria
        • Not yet recruiting
        • Niger Delta Teaching Hospital
        • Contact:
          • Dimie Ogoina, MD
      • Port Harcourt, Nigeria
        • Not yet recruiting
        • University of Port Harcourt Teaching Hospital
        • Contact:
          • Datonye Alasia, MD
  • Uganda
      • Kampala, Uganda
        • Not yet recruiting
        • Makerere University Lung Institute
        • Contact:
          • Bruce Kirenga, PhD
        • Contact:
          • Winters Muttamba, MD

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

10 years and older (Child, Adult, Older Adult)

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

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

Exclusion Criteria:

  1. Pregnancy
  2. Breastfeeding
  3. Past serious allergic reaction to study vaccine components
  4. Previous smallpox vaccination
  5. Current or planned use of another investigational drug at any point during study participation

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Prevention
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Triple

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Smallpox vaccine
Participants will receive the Bavarian Nordic smallpox vaccine 0.5 ml single-dose
Drug: Bavarian Nordic smallpox vaccine
A single dose of the Bavarian Nordic smallpox vaccine will be given at baseline.
Other Names:
  • Imvamune
Active Comparator: Typhoid vaccine
Participants will receive the Typhim Vi® typhoid vaccine 0.5 ml single-dose
Drug: Typhoid VI Polysaccharide Vaccine Injectable Solution
A single dose of the typhoid vaccine will be given at baseline.
Other Names:
  • Typbar

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
PCR-confirmed Mpox
Time Frame: 8 weeks
To evaluate if smallpox vaccine vs control prevents RT-PCR confirmed mpox
8 weeks
Symptom severity
Time Frame: 8 weeks
To evaluate if smallpox vaccine vs control affects symptom severity
8 weeks

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Resolution of skin lesions
Time Frame: 8 weeks
To assess the time to resolution (i.e. a new skin layer has formed) of any skin lesion
8 weeks
Number of skin lesions
Time Frame: 8 weeks
To assess the number of skin lesions for any participants who develop mpox
8 weeks
Self-reported Quality of Life
Time Frame: 8 weeks
To assess the QOL of participants using the World Health Organization Quality of Life Scale
8 weeks
Mpox complications
Time Frame: 8 weeks
To assess longitudinal complications for any participants who develop mpox
8 weeks
Mpox Pain
Time Frame: 8 weeks
To assess pain using an adapted Zoster Brief Pain Inventory
8 weeks
Hospitalization
Time Frame: 8 weeks
To determine all cause hospitalization over the study period
8 weeks
Mortality
Time Frame: 8 weeks
To determine all cause mortality over the study period
8 weeks

Other Outcome Measures

Outcome Measure
Measure Description
Time Frame
Safety (SAEs, AESI)
Time Frame: 6 months
Solicited SAE and AESIs will be followed at 4 months and 6 months
6 months

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

McMaster University

Investigators

  • Principal Investigator: Mark Loeb, MD, McMaster University

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

September 17, 2024

Primary Completion (Estimated)

June 1, 2026

Study Completion (Estimated)

December 1, 2026

Study Registration Dates

First Submitted

February 10, 2023

First Submitted That Met QC Criteria

February 16, 2023

First Posted (Actual)

February 27, 2023

Study Record Updates

Last Update Posted (Actual)

July 6, 2025

Last Update Submitted That Met QC Criteria

July 3, 2025

Last Verified

July 1, 2025

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • SMART RCT

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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