Speaker
Description
Mpox denotes a viral zoonosis caused by the Orthopoxvirus monkeypox (MPXV), which is endemic in West and Central Africa. In spring 2022, notable outbreaks of MPXV clade IIb were recorded in several high-income countries, predominantly affecting men who have sex with men (MSM). At the peak of the outbreak, over 200 new Mpox cases per week were reported in Berlin, which constitutes one of the largest MSM communities in Europe. Within the same year, the outbreak significantly declined, and it is unclear which factors contributed to these dynamics.
To investigate the concomitant effects of sexual contact networks, transient contact reductions and the effect of infection- vs. vaccine-derived immunity on the 2022 Mpox outbreak, we calibrated an agent-based model with epidemic, vaccination, contact- and behavioural data.
Our results indicated that the vaccination campaign had a marginal effect on the epidemic decline. Rather, a combination of infection-induced immunity of high-contact individuals, as well as transient behaviour changes reduced the number of susceptible individuals below the epidemic threshold. This emphasizes that, in addition to vaccination, timely and clear communication of transmission routes may trigger spontaneous protective behaviour within key populations; highlighting the importance of targeted sexual health education as a component of outbreak response.
While there were no reported Mpox cases in Berlin during the first half of 2023, clade IIb cases began to re-surge and stabilize in 2024 and 2025 in addition to a surge of clade I cases in 2026. By expanding the model with data up to the end of 2025, as well as genomic surveillance data, we intend to quantify the impact of return to pre-pandemic contact behaviour ("pandemic deficit"), waning vaccine protection, and extensive cryptic circulation on the persistence of clade II.
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