Determinants of mpox vaccination uptake among MSM during the 2022 outbreak: a single-centre retrospective study at Lyon University Hospital, France

Abstract Background During the 2022 mpox outbreak, prophylactic vaccination was offered to at risk individuals, including men who have sex with men (MSM) with multiple sexual partners. We aimed to evaluate mpox vaccine first dose uptake in MSM and its determinants. Methods We conducted a single-centre, retrospective study using data from MSM presenting at the STI and HIV clinics of Lyon University Hospital between 1 January 2022 and 28 February 2023. First dose uptake of mpox vaccination (modified vaccinia Ankara-Bavarian Nordic) was evaluated across three groups of MSM: people living with HIV (PWH), HIV pre-exposure prophylaxis (PrEP) users and non-PrEP users (NPU). Uptake rates were compared with Chi2 analysis and multivariable hazard ratios (HR) were calculated using a Cox model. Results A total of 9,256 MSM (PWH, n = 1,946; PrEP, n = 2,528; NPU, n = 4,782) were included. By February 2023, the first dose uptake rate was 49.6% (4,590/9,256). PrEP users were more likely to get vaccinated (72.2%) than PWH (32.7%, p < 0.0001) and NPU (44.5%, p < 0.0001). Half of PrEP users had been vaccinated by day 67 of the vaccination campaign. In multivariable analysis, an age ≤ 25 yo (HR, 0.35 [95% confidence interval (CI), 0.32–0.38]), as well as an age > 60 yo (HR, 0.83 [95% CI, 0.72–0.95]) and HIV infection (HR, 0.46 [95% CI, 0.41–0.50]) were associated with a lower first dose uptake, as opposed to PrEP use (HR, 1.69 [95% CI, 1.59–1.81]) and chemsex (HR, 1.42 [95% CI, 1.30–1.54]). Conclusions In this large cohort of MSM, first dose uptake was high, especially in PrEP users. Among MSM at risk for mpox, PWH and younger individuals should be priority targets for vaccine promotion.