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

NCT05745987 | Active Not Recruiting Phase 4 DMC

• 1 other identifier: SMART RCT
• Study Type: interventional
• Target: 3,000
• Locations: 3 countries
• Sites: 10

Brief Summary

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

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

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 vaccine DRUG

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 Solution DRUG

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

Typhoid vaccine

Eligibility Criteria

• Age: 2 Years+
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Child (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

Sponsors & Collaborators

• McMaster University: lead

Study Sites (10)

Catholic University of Bukavu

Kinshasa, Bukavu, Democratic Republic of the Congo

Location

Federal Medical Center

Abuja, Nigeria

Location

University of Abuja Teaching Hospital

Abuja, Nigeria

Location

University of Ibadan

Ibadan, Nigeria

Location

Irrua Specialist Teaching Hospital

Irrua, Nigeria

Location

Aminu Kano Teaching Hospital

Kano, Nigeria

Location

Lagos University Teaching Hospital

Lagos, Nigeria

Location

Niger Delta Teaching Hospital

Okolobiri, Nigeria

Location

University of Port Harcourt Teaching Hospital

Port Harcourt, Nigeria

Location

Makerere University Lung Institute

Kampala, Kampala, Uganda

Location

MeSH Terms

Conditions

Mpox, Monkeypox

Interventions

smallpox and monkeypox vaccine modified vaccinia ankara-bavarian nordic

Condition Hierarchy (Ancestors)

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

Study Officials

• Mark Loeb, MD

  McMaster University

  PRINCIPAL INVESTIGATOR

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
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Model Details: Each group will be randomly selected to receive the smallpox vaccine or the typhoid vaccine

Study Record Dates

• First Submitted: February 10, 2023
• First Posted: February 27, 2023
• Study Start: September 17, 2024
• Primary Completion: April 22, 2026
• Study Completion (Estimated): October 20, 2026
• Last Updated: August 12, 2026

Record last verified: 2026-08

Data Sharing

• IPD Sharing: Will not share

Locations

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