Polio vaccination coverage in Gaza has reached 90%, the head of the United Nations Palestinian refugee agency said on Monday, adding that the next step was to ensure hundreds of thousands of children got a second dose at the end of the month.

The campaign to vaccinate some 640,000 children in Gaza under 10 years of age against polio, which began on Sept. 1, presented major challenges to UNRWA and its partners due to the ongoing conflict between Israel and Hamas.

It followed confirmation by the World Health Organization (WHO) last month that a baby had been partially paralysed by the type 2 polio virus, the first such case in the Palestinian territory in 25 years.

More than 446,000 Palestinian children in central and south Gaza were vaccinated earlier this month before a campaign to vaccinate a final 200,000 children in north Gaza began on September 10 despite access restrictions, evacuation orders and shortages of fuel.

The first round of the polio vaccination campaign in Gaza ended successfully, UNRWA's chief Philippe Lazzarini said, adding that 90% of the enclave's children had received a first dose.

"Parties to the conflict have largely respected the different required "humanitarian pauses" showing that when there is a political will, assistance can be provided without disruption. Our next challenge is to provide children with their second dose at the end of September," he wrote on X.

Israel began its military campaign in Gaza on Oct. 7 last year after Hamas led a shock incursion into southern Israel, killing about 1,200 people and taking about 250 hostages, according to Israeli tallies.

The resulting assault on Gaza has killed more than 41,000 Palestinians, according to the enclave's health ministry, and reduced much of the territory to rubble.