Fig. 1: Application of MPXV nomenclature schemes in relation to sustained H2H transmission outbreaks.

MPXV clades, clade Ia phylogenetic groups, clade IIb lineages and lineages associated with sustained H2H outbreaks (as proposed in this article) are labeled. Red phylogenetic branches are within sustained H2H outbreaks; sustained H2H transmission lineages are designated to coincide with the start of these outbreaks. We assembled a dataset containing clade Ia, clade Ib, clade IIa and clade IIb non-lineage B.1 genome sequences included in ref. ¹⁴, representative sequences from clade IIb lineage B.1 and descendant lineages (https://github.com/mpxv-lineages/lineage-designation/) and sequences that cluster within clade Ia/sh2024 (ref. ⁹). Sequences were aligned using squirrel (https://github.com/aineniamh/squirrel) and a phylogenetic tree reconstructed with IQ-TREE v2.1.3 (ref. ¹⁵) using the Jukes–Cantor (JC) model of nucleotide substitution. The scale bar shows the expected number of nucleotide substitutions per site. The inferred clustering of clade Ib sequences collected from Nord- and Sud-Kivu, DRC, in 2011 and 2012 (ref. ¹²) that do not belong to the sustained H2H outbreak is noted at far right⁷.