A new deadlier strain of mpox that transmits more easily between people is killing children and causing miscarriages in Congo and may have already spread to neighboring countries, researchers have warned.

All countries should be preparing for "this new strain before it spreads to other places, before it is too late," Jean Claude Udahemuka, a researcher at the University of Rwanda studying the outbreak, said.

A global outbreak of a new strain of mpox — previously known as monkeypox — in 2022 spread to more than 110 countries, mostly affecting gay and bisexual men. That was the clade II strain.