Wiping out smallpox had an unintended consequence: the rise of mpox in the past few years. Here's the story — starting with patient zero for mpox back in 1970.

Congo has over 20,000 cases of mpox and hundreds of deaths, mostly in children, but zero vaccines until now. A planeload of doses donated from the EU landed in Kinshasa on Thursday.

"What we're seeing is tip of the iceberg" because of weaknesses in the surveillance system, says Dr. Dimie Ogoina, chair of the WHO's emergency committee.

This would be the first ever emergency declaration for the African continent. What's the reason for this sense of urgency?

A cluster of mpox cases in the Chicago area has sparked fears of a summer wave. Health officials are pointing to new research showing the vaccine is effective and hoping people take notice.