A fresh polio outbreak in Sudan was triggered by a vaccine-derived virus from Chad, WHO announced yesterday.
WHO declared Africa wild poliovirus-free last week—but that good news was tempered by the possibility of vaccine-derived outbreaks like this one. In rare cases, the live poliovirus used in the oral vaccine can mutate and trigger new outbreaks.
- 2 recently vaccinated children in Sudan were paralyzed in March and April.
- WHO has identified 11 other cases though officials case numbers likely underestimate the scope of the outbreak.
- The virus has also been found in environmental samples.