Poliovirus continues to pose a global public health threat, with both wild and vaccine-derived viruses detected in clinical and environmental samples, including in countries declared to be polio free.

In its original form, the virus survives in just two countries. But a type linked to an oral vaccine used in other nations has already turned up in the West. By Apoorva Mandavilli Most American ...

Add Yahoo as a preferred source to see more of our stories on Google. (Reuters) -The World Health Organisation said on Tuesday that circulating vaccine-derived poliovirus type 2 (cVDPV2) had been ...