In other developments, health officials have reported in utero spread of the virus and the first case of the year in North Africa.
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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In Burundi's worsening outbreak, kids younger than 15 are the most affected group, similar to the DR Congo.
The DRC's health ministry could begin deploying the vaccine, donated by the European Commission, this weekend.
The step paves the way for purchase and shipping, as other factors fall into place.
The agency made a similar request to vaccine companies earlier this month. Meanwhile, Kenya reported its third case, in a Nairobi resident who had been in Uganda.
Officials have deployed 72 epidemiologists to affected countries to get a better idea of where and how mpox is spreading.
The plan sets out a strategy for the next 6 months, with an estimated $135 million needed for support.
More than 25% said they had misdiagnosed someone initially.
In an update, the WHO notes widespread activity across Burundi, including in an urban area.
The new funding brings US support for the outbreak response to $55 million.
As more groups offer vaccine donations, cases are spiking in Burundi, one of the newly affected countries.
