Officials have voiced concerns that Israel’s evacuation orders for northern Gaza might affect the second polio vaccination campaign set to start next week, Al Jazeera reports.

“I am concerned about the developments in the north, and specifically with these evacuation orders,” Rik Peeperkorn, WHO representative for the occupied Palestinian territory, told reporters in Geneva.

Jean Gough, Unicef special representative in the State of Palestine, also voiced concerns and described the conditions as “more complicated” than in the first phase of the vaccination campaign last month.