Wide-scale use of monovalent oral polio vaccine type 1 (mOPV1) continues to have a significant impact on curbing transmission of this particular virus serotype. It is the more dangerous of the two remaining virus types, given its historically higher disease burden and ability to spread internationally. Only three type 1 cases have been reported this year from the western part of Uttar Pradesh state, India, arguably the most historically entrenched type 1 reservoir in the world.

At the same time, no type 1 cases have been reported in Kano, Nigeria, since October 2006 – a remarkable achievement, given that Kano was the epicenter of a major international epidemic which re-infected 20 previously polio-free countries in 2003-2006.

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