Key Points

• From January 1 through September 30, 2026, 427 cases of smallpox B (mpox) were reported, including 18 cases without laboratory confirmation.
• Among the cases for which the clade could be identified, 82% (275/337) belonged to clade Ib, compared with 18% (62/337) belonging to clade IIb.
• The reported cases involved 385 males (90%) and 42 females (10%). With the exception of 3 cases in children (<15 years old), all reported cases were adults with a median age of 35 years. More than one-third of the cases resided in Île-de-France (170/427, 40%); 18% resided in the Indian Ocean departments (49/427 in Mayotte and 27/427 in Réunion) and 9% in the Grand Est region (40/427).
• In terms of risk exposures, 34% of documented cases (142/416) reported contact with a case within the 3 weeks prior to the onset of their symptoms. Of the 112 men who reported contact with a case, 88 (79%) indicated that the contact was with a sexual partner. Among the cases for which travel history was reported, 34% (137/404) had traveled abroad within the 3 weeks prior to the onset of their symptoms, primarily to sub-Saharan Africa (including 59 in Madagascar, 4 in Côte d’Ivoire, and 3 in Guinea) and in Europe (including 30 in Spain, 6 in Germany, 5 in Belgium, and 5 in Italy).
• Among the 417 cases for which information was available, 43 (10%) were hospitalized, primarily for the management of severe pain (n=28 cases) and/or generalized rashes (n=21 cases).
• Regarding vaccination status, when known, 77% (269/350) had not received any vaccine doses since May 2022. Among the 81 vaccinated cases, 26 had received only one dose (including 6 who had been vaccinated prior to 1984), 34 had received two doses (including 2 vaccinated individuals with a history of vaccination prior to 1984), and 9 had received three doses. The number of doses received since 2022 was unknown for 12 cases.