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NCT Number: NCT05745987

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

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

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Key information

Conditions

Monkeypox Animal Diseases DNA Virus Infections Infections Mpox, Monkeypox Poxviridae Infections Primate Diseases Rodent Diseases Virus Diseases

Age range

2 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Phase 4

Primary location

Catholic University of Bukavu, Kinshasa, Bukavu, Democratic Republic of the Congo

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About this study

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.

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

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

Exclusion criteria

  • 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

Treatment and study plan

Bavarian Nordic smallpox vaccine

Drug

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

Other names: Imvamune

Typhoid VI Polysaccharide Vaccine Injectable Solution

Drug

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

Primary outcomes

  1. PCR-confirmed Mpox

    Time frame: 8 weeks

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

  2. Symptom severity

    Time frame: 8 weeks

    To evaluate if smallpox vaccine vs control affects symptom severity

Secondary outcomes

  1. 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

  2. Number of skin lesions

    Time frame: 8 weeks

    To assess the number of skin lesions for any participants who develop mpox

  3. Self-reported Quality of Life

    Time frame: 8 weeks

    To assess the QOL of participants using the World Health Organization Quality of Life Scale

  4. Mpox complications

    Time frame: 8 weeks

    To assess longitudinal complications for any participants who develop mpox

  5. Mpox Pain

    Time frame: 8 weeks

    To assess pain using an adapted Zoster Brief Pain Inventory

  6. Hospitalization

    Time frame: 8 weeks

    To determine all cause hospitalization over the study period

  7. Mortality

    Time frame: 8 weeks

    To determine all cause mortality over the study period

Other outcomes

  1. Safety (SAEs, AESI)

    Time frame: 6 months

    Solicited SAE and AESIs will be followed at 4 months and 6 months

Study contacts

Contact information is provided by the study sponsor or research team.

Mark Loeb, MD

CONTACT

[email protected]

9055259140

Sponsors and collaborators

Lead sponsor

McMaster University

Other

Registry information

Official study title

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

Acronym: SMART

Important dates

Study start
2024
Primary completion
2026
Study completion
2026
First posted
Feb 27, 2023
Registry last updated
Jul 6, 2025

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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