Key Points

• From January 1 to August 31, 2026, 359 cases of smallpox B (mpox) were reported, including 15 without laboratory confirmation.
• Among the cases for which the clade could be identified, 78% (220/281) belonged to clade Ib, compared with 22% (61/281) belonging to clade IIb.
• The reported cases involved 321 males (89%) and 38 females (11%). With the exception of 3 cases in children (<15 years old), all reported cases were adults with a median age of 34 years. More than one-third of the cases resided in Île-de-France (140/359, 39%); 21% resided in the Indian Ocean departments (49/359 in Mayotte and 27/359 in Réunion) and 10% in the Grand Est region (36/359).
• In terms of risk exposures, 34% of documented cases (117 out of 348) reported contact with a case within the 3 weeks prior to the onset of their symptoms. Of the 90 men who reported contact with a case, 70 (78%) indicated that the contact was with a sexual partner. Among cases for which travel history was available, 35% (119/340) had traveled abroad within the 3 weeks prior to the onset of their symptoms, primarily to Europe (including 23 to Spain, 7 to Germany, and 5 to Belgium) or to sub-Saharan Africa (including 57 to Madagascar, 4 to Côte d’Ivoire, and 3 to Guinea).
• Among the 349 cases for which this information was available, 33 (9%) were hospitalized, primarily for the management of severe pain (n = 24 cases) and/or generalized rashes (n = 18 cases).
• Regarding vaccination status, when known, 78% of cases (226/291) had not received any vaccine doses since May 2022. Among the 65 vaccinated cases, 24 had received only one dose (including 5 vaccinated before 1984), 28 had received two doses (including 2 vaccinated before 1984), and 6 had received three doses. The number of doses received since 2022 was unknown for 7 cases.