Vaccine-Derived Outbreak in Sudan

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.

Details:  

• 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.

AP