WHO says early polio vaccination targets in Gaza surpassed

With Gaza lying in ruins and the majority of the 2.4 million residents forced to flee their homes due to Israel's military assault -- often taking refuge in cramped and unsanitary conditions -- disease has spread.

After the first confirmed polio case in 25 years, a large-scale vaccination drive began on Sunday, with localised "humanitarian pauses" in fighting.

The campaign aims to fully vaccinate more than 640,000 children in the besieged territory, devastated by almost 11 months of war.

Peeperkorn said it was vital to reach at least 90-percent coverage to avoid the spread of the disease, which mainly affects children under five, can cause deformities and paralysis, and is potentially fatal.

The campaign began in the central part of the densely populated Gaza Strip, where the WHO initially expected to vaccinate 156,500 children under the age of 10.

"Our target for the central zone was an underestimation," Peeperkorn said, adding this was probably due to an underestimate of the population crowded into the area.

He said the vaccination drive was expected to shift to southern Gaza on Thursday, to immunise some 340,000 children there.

It would then move to the north of the Strip, where around 150,000 will be vaccinated.

"We still have 10 days to go at least" for the whole first portion of the campaign, Peeperkorn said, and the rollout of the necessary second dose would begin in four weeks.

Israel's military assault on Gaza since October has so far killed at least 40,819 people there, according to the territory's health ministry.

The United Nations rights office says most of the dead are women and children.

War has been raging in the Palestinian territory since an attack in Israel on October 7 by fighters from the Palestinian group Hamas.

That attack resulted in the deaths of 1,205 people, mostly civilians and including hostages taken by Hamas, according to an AFP tally based on Israeli official figures.