Real-world effectiveness of a single dose of mpox vaccine in males.

The recent global outbreak of the monkeypox (mpox) virus in humans was declared a public health emergency by the World Health Organization in July 2022. The smallpox and mpox vaccine (JYNNEOS; Modified Vaccinia Ankara-Bavarian Nordic; MVA-BN), provided as a two-dose regimen, is currently the primary vaccine utilized against mpox. However, the efficacy of MVA-BN against mpox has never been demonstrated in clinical trials to date. Due to the limited supply of vaccines, the World Health Organization has recommended prioritizing the vaccination of high-risk groups. We evaluated the real-world effectiveness of a single, subcutaneous dose of MVA-BN in this observational, retrospective cohort study, which included the analysis of electronic health records of all members of Clalit Health Services eligible for the vaccine on 31 July 2022. We used a Cox proportional hazards regression model with time-dependent covariates to estimate the association between vaccination and mpox while adjusting for sociodemographic and clinical risk factors. In an analysis of 2,054 male individuals who met vaccine eligibility criteria, 1,037 (50%) were vaccinated during the study recruitment period and completed at least 90 d of follow-up. During the study period, 5 and 16 infections were confirmed in vaccinated and unvaccinated individuals, respectively. The adjusted vaccine effectiveness was estimated at 86% (95% confidence interval, 59-95%). Our results suggest that a single dose of subcutaneous MVA-BN in this high-risk cohort is associated with a significantly lower risk of MPXV infection.

Risk assessment of human mpox infections: retrospective cohort study.

OBJECTIVES: The global supply of vaccines against mpox (previously called monkeypox virus infection) was significantly lower than the demand. Therefore, evidence-based vaccine prioritization criteria, based on risk assessment were needed. Our objective was therefore to identify the characteristics of individuals at the highest risk for mpox. METHODS: This population-based cohort study included all Clalit Health Services (CHS) subjects assumed to be at risk for mpox. The eligibility criteria for inclusion were determined based on known characteristics of people with infection worldwide and insights of lesbian, gay, bisexual, transgender, queer+ (LGBTQ+) -specialized CHS clinicians. Cox hazards models were used to identify the risk factors for mpox within the study cohort. The study commenced on 6 June 2022, the date of the first known mpox in CHS members, until 31 July 2022, when the mpox vaccination campaign started. RESULTS: A total of 8088 individuals of 4.7 million CHS members (0.18%) were identified according to the study inclusion criteria. Of those, 69 (0.85%) developed infection during the study period. Risk factors for mpox were birth in 1980 or later (hazard ratio, 5.04; 95% CI, 2.11-12.02), history of syphilis (2.62; 1.58-4.35), registration to primary healthcare clinics in the Tel Aviv district (2.82; 1.44-5.54), HIV-pre-exposure prophylaxis medication use (3.96; 2.14-7.31), PDE5 inhibitors use (2.92; 1.77-4.84), and recent sexually transmitted infections (STIs) within the last 18 months (2.27; 1.35-3.82). No infections were observed in individuals with none of the factors. Individuals with three or more risk factors had a 20.30-fold (10.39-39.69) higher risk for mpox compared with those with 0-2, with 85.5% (75.0-92.8%) sensitivity and 77.8% (76.9-78.7%) specificity. DISCUSSION: Weighting individuals' risk levels based on validated risk factors against vaccine availability can assist health systems in the equitable prioritization of vaccine allocation in various future outbreaks, given supply-demand gaps.