Epidemiological characteristics of monkeypox virus Clade Ib in the Democratic Republic of the Congo

Monkeypox virus (MPXV) Clade Ib, a new MPXV subclade associated with sustained human-to-human transmission, emerged in eastern DRC in late 2023. Early spread mainly occurred among the adult population, primarily through sexual contact. We investigate how key epidemiological characteristics of the new MPXV Clade Ib outbreak in the DRC differ by transmission mode. We estimate the mean serial interval to be 8.57 days (95% CI 7.15 - 9.91 days). The serial interval is approximately four days shorter for putative sexual compared to non-sexual transmission. We estimate the mean incubation period to be 9.56 days (95% CrI 8.22 - 11.02 days), and approximately two days shorter for putative sexual compared to non-sexual transmission. These observed differences in serial interval and incubation period estimates by transmission mode suggest that the context in which an outbreak occurs is an essential factor to consider when devising public health policies.