The World Health Organization is urging Ukraine's health ministry to declare a state of emergency due to a polio outbreak, a move meant to prompt more action from the government in Kiev.
In September, Ukraine announced two polio cases - the first in Europe since 2010.
The U.N. health agency recommended that Ukraine declare a state of emergency and "respond to the polio outbreak as quickly and effectively as possible," Dorit Nitzan, head of the WHO's office in Ukraine, told journalists.
Half of Ukraine's children have not been vaccinated against polio.
Polio is a highly infectious, paralyzing disease on the brink of elimination. Aside from Ukraine, cases have only been reported in six other countries this year, with the majority in Pakistan and Afghanistan.