Table 1.

Notable differences in the signs and symptoms of illness from classic mpox compared with illness due to the 2022 multinational Clade IIb outbreak strain.

Sign/symptom	Classic	2022 outbreak
Prodrome (e.g. fever, headache, malaise or fatigue, lymphadenopathy)	At least one sign or symptom appears before rash	Variable: signs and symptoms may be absent or occur after rash appears
Lesion distribution	Multiple lesions distributed diffusely and centripetally often involving palms and soles	Fewer or even single lesions that can be limited to only one anatomic area with a more centrifugal distribution
Anogenital lesions	Uncommon	Common: often presenting symptom
Lesion progression	Lesions appear and progress synchronously	Lesions may appear in asynchronous crops that progress separately