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

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

Detailed Description
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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.

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

Conditions
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Monkeypox

Intervention / Treatment
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* Drug: Bavarian Nordic smallpox vaccine
* Drug: Typhoid VI Polysaccharide Vaccine Injectable Solution


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Household member of person with laboratory confirmed mpox Age ≥ 10 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

Ages Eligible for Study
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Minimum Age: 10 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Prevention
Allocation: Randomized
Intervention Model: Parallel Assignment
Interventional Model Description: Each group will be randomly selected to receive the smallpox vaccine or the typhoid vaccine
Masking: Triple


Arms and Interventions

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

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| PCR-confirmed Mpox | To evaluate if smallpox vaccine vs control prevents RT-PCR confirmed mpox | 4 weeks | 
| Symptom severity | To evaluate if smallpox vaccine vs control affects symptom severity | 4 weeks | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Resolution of skin lesions | To assess the time to resolution (i.e. a new skin layer has formed) of any skin lesion | 4 weeks | 
| Number of skin lesions | To assess the number of skin lesions for any participants who develop mpox | 4 weeks | 
| Self-reported Quality of Life | To assess the QOL of participants using the World Health Organization Quality of Life Scale | 4 weeks | 
| Mpox complications | To assess longitudinal complications for any participants who develop mpox | 4 weeks | 
| Mpox Pain | To assess pain using an adapted Zoster Brief Pain Inventory | 4 weeks | 
| Hospitalization | To determine all cause hospitalization over the study period | 4 weeks | 
| Mortality | To determine all cause mortality over the study period | 4 weeks | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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mpox