Effectiveness of a single-dose Modified Vaccinia Ankara in Human Monkeypox: an observational study

Abstract

Background The recent global outbreak of the human monkeypox virus (MPXV) was declared a public health emergency by the World Health Organization. Modified Vaccinia Ankara (MVA) is currently the only FDA-approved vaccine against MPXV that was approved for this indication based on a study in non-human primates. Since there is currently scarce evidence of the efficacy in humans, our objective was to evaluate real-life vaccine effectiveness (VE) after providing one vaccine dose to individuals at risk of MPVX infection. Methods The study cohort included all Clalit Health Services (CHS) members eligible for the MVA vaccine as defined by the Israeli Ministry of Health. The study commenced on July 31, 2022, when the MVA vaccination campaign was initiated in CHS, and participants were followed until September 12, 2022. A Cox proportional-hazards regression model with time-dependent covariates was used to estimate the association between vaccination and MPXV infections with adjustment for sociodemographic and clinical risk factors. Findings A total of 1,970 subjects met the study eligibility criteria (0.04% of CHS members). Of them, 873 (44%) were vaccinated with MVA and completed at least 25 days of follow-up. 18 infections were confirmed in CHS during the study period, 3 in vaccinated and 15 in unvaccinated status (40.0 versus 6.4 per 100,000 person days). VE was estimated at 79% (95% CI: 24%-94%). Interpretation Our results suggest that a single dose of MVA is associated with a significantly lower risk for MPVX infection in high-risk individuals. These findings highlight that urgent MVA vaccination of high-risk individuals may contribute to the containment of the current MPXV outbreak.

Reduced Risk for Mpox After Receipt of 1 or 2 Doses of JYNNEOS Vaccine Compared with Risk Among Unvaccinated Persons — 43 U.S. Jurisdictions, July 31–October 1, 2022

“…Further, increased completeness of vaccination administration date (from 43% to 82% completeness) and a better-fitting statistical model yielded more precise effect estimates. These findings are consistent with those of the previous analysis as well as recent studies reporting some protection (7) and modest induction of antibody levels (8,9) after the first JYNNEOS vaccine dose.…”

Incidence of Monkeypox Among Unvaccinated Persons Compared with Persons Receiving ≥1 JYNNEOS Vaccine Dose — 32 U.S. Jurisdictions, July 31–September 3, 2022

“…Data for this analysis were collected during a period when vaccine was widely available, reducing potential bias from limited vaccine accessibility. Findings are consistent with recent studies reporting that a single dose of JYNNEOS vaccine for prevention of MPXV infection in males aged 18–42 years who were prescribed HIV-PrEP or with diagnosed HIV infection and one or more other sexually transmitted infection might provide some protection ( 7 ) and modest induction of antibody levels after a single dose ( 8 ).…”

Effectiveness of one dose of MVA-BN smallpox vaccine against monkeypox in England using the case-coverage method

“…Our estimates are consistent with the recent Israeli study, which estimated a VE of 79% (95% CI: 24%-94%) after a single dose of MVA-BN in a similar cohort of highrisk GBMSM aged 18-42 years using an electronic healthcare system that covers around 52% of the Israeli population. 19 The eligible cohort in this study was similar to the cohort in our study: male subjects at high risk of infection, defined by similar criteria to those in England. 19 Only subjects aged 18-42 were including, likely excluding any subjects who might have received childhood smallpox vaccinations, which would be comparable to our <50 analysis.…”

“…19 The eligible cohort in this study was similar to the cohort in our study: male subjects at high risk of infection, defined by similar criteria to those in England. 19 Only subjects aged 18-42 were including, likely excluding any subjects who might have received childhood smallpox vaccinations, which would be comparable to our <50 analysis. The analysis did not report VE within and after 14 days, with a follow-up interval of 25 days after vaccination.…”