Real-world effectiveness of MBA-VN vaccine against mpox, a test-negative case-control study

Area of Science:

• Infectious Diseases
• Vaccinology
• Public Health

Background:

• Mpox (viral illness) outbreak in 2022 led to MVA-BN vaccine authorization.
• Limited real-world evidence exists on MVA-BN vaccine effectiveness (VE) despite high immunogenicity.
• Study focuses on symptomatic mpox in adults tested at a Barcelona tertiary hospital.

Purpose of the Study:

• To estimate the real-world VE of at least one MVA-BN vaccine dose against symptomatic mpox.
• To assess VE in adults tested for mpox between July 2022 and December 2023.

Main Methods:

• Test-negative case-control study design.
• Inclusion of adults tested for mpox via PCR (cases: PCR-positive, controls: PCR-negative).
• Calculation of VE using multivariable logistic regression: (1 - adjusted odds ratio) × 100%.

Main Results:

• 301 participants: 126 cases, 175 controls.
• Crude VE (≥1 dose ≥14 days prior) was 47%.
• Adjusted VE: 74% (sex, age, center, STI history, risk criteria); 44% (additionally adjusted for epidemiological weeks).
• Similar patterns observed in men with mpox risk criteria.

Conclusions:

• Provides context-specific, real-world VE data for a single MVA-BN vaccine dose against symptomatic mpox.
• VE estimates varied significantly based on adjustment strategies.
• Emphasizes the critical need to account for epidemiological weeks to prevent overestimation of mpox VE.