On viral culture, 4 of 21 environmental samples (19%) contained infectious virus.
The test the US Centers for Disease Control and Prevention uses to identify clade I mpox cases is 'most likely not reliable' for detection of the substrain identified in the study, the authors say.
Another mpox study today showed that dose-sparing vaccine administration of the Jynneos vaccine appeared to have worked.
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Responding to the surge is a major focus, partly to prevent the spread to other West African countries.
Sierra Leone is averaging 100 new cases a day, fueled by the clade 2b virus.
Some of the key steps have included deployment of more community health workers and decentralized lab testing.
Cases are declining in some hot spot countries, as officials warns that nations outside Africa are still reporting imported cases.
The median number of days to lesion clearance was 7 with Tpoxx and 8 with placebo.
Clade 1b is fueling a central Africa mpox outbreak, with the Democratic Republic of the Congo seeing the most cases.
Earlier patients had traveled to outbreak countries or were contacts of earlier cases.
Ghana reported its first recurrence in many weeks, as cases rise in Tanzania and responders launch a second vaccination round in Uganda.
The freeze-dried Jynneos formulation will be easier to store and transport and will have a longer shelf life.
In its monthly mpox update, the WHO said it is tracking several genetic developments, including rising cases of the rare 2b clade.
