Effectiveness of Modified Vaccinia Ankara-Bavaria Nordic Vaccination in a Population at High Risk of Mpox: A Spanish Cohort Study
Authors: Fontán-Vela Mario , Hernando Victoria , Olmedo Carmen , Coma Ermengol , Martínez Montse , Moreno-Perez David , Lorusso Nicola , Vázquez Torres María , Barbas del Buey José Francisco , Roig-Sena Javier , Pastor Eliseo , Galmés Truyols Antònia , Artigues Serra Francisca , Sancho Martínez Rosa María , Latasa Zamalloa Pello , Pérez Martínez Olaia , Vázquez Estepa Ana , García Rojas Amós José , Barreno Estévez Ana Isabel , Sánchez-Migallón Naranjo Alonso , Pérez Martín Jaime Jesús , Peces Jiménez Pilar , Morales Romero Raquel , Castilla Jesús , García Cenoz Manuel , Huerta Huerta Marta , Boone An Lieve Dirk , Macías Ortiz María José , Álvarez Río Virginia , Rodríguez Recio María Jesús , Merino Díaz María , Berradre Sáenz Belén , Villegas-Moreno María Teresa , Limia Aurora , Diaz Asuncion , Monge Susana ,   Spanish MPOX Vaccine Effectiveness Study Group, Rodrigo José Antonio Lluch , Juaneda Juan , Malonda Rosa Carbo , Mendioroz Jacobo , Farran Joan Colom , Carril Fernando González , Echevarría Lorea Oscoz , Barros María Teresa Otero , Gaiche Nuria Suárez , Martínez José Angélica Gómez , Bastante Borja Alcázar , Santos Rocío Sánchez , Sanjurjo Lucía Fuster , del Carmen Pacheco Martínez María , Cruz Nancy Coromoto , Hernández Laura García , Martín Óscar Guillermo Pérez , García Marcos Alonso , Rodríguez María Ángeles Gutiérrez , Centeno Beatriz López , Martins Mario Margolles , Ochoa Eva Martínez , Jiménez-Murillo José Luis , de Celis Miguel Mingo Gómez , Jarrín Inma , Guzmán Bernardo , Suárez Berta 
Published: October 2023

Abstract

Background
With more than 7500 cases reported since April 2022, Spain has experienced the highest incidence of mpox in Europe. From 12 July onward, the modified vaccinia Ankara-Bavaria Nordic (MVA-BN) smallpox vaccine was offered as pre-exposure prophylaxis for those receiving pre-exposure prophylaxis for human immunodeficiency virus (HIV-PrEP). Our aim was to assess the effectiveness of 1 dose of MVA-BN vaccine as pre-exposure prophylaxis against mpox virus (MPXV) infection in persons on HIV-PrEP.

Methods
National retrospective cohort study between 12 July and 12 December 2022. Individuals aged ≥18 years receiving HIV-PrEP as of 12 July with no previous MPXV infection or vaccination were eligible. Each day, we matched individuals receiving a first dose of vaccine and unvaccinated controls of the same age and region. We used a Kaplan–Meier estimator, calculated risk ratios (RR) and vaccine effectiveness (VE = [1 − RR]x100).

Results
We included 5660 matched pairs, with a median follow-up of 62 days (interquartile range, 24–97). Mpox cumulative incidence was 5.6 per 1000 (25 cases) in unvaccinated and 3.5 per 1000 (18 cases) in vaccinated. No effect was found during days 0–6 post-vaccination (VE, −38.3; 95% confidence interval [CI], −332.7 to 46.4), but VE was 65% at ≥7 days (95% CI, 22.9 to 88.0) and 79% at ≥14 days (95% CI, 33.3 to 100.0) post-vaccination.

Conclusions
One dose of MVA-BN vaccine offered protection against mpox in most-at-risk population shortly after the vaccination. Further studies need to assess the VE of a second dose and the duration of protection over time.