GAZA –  More than 560,000 children aged below 10 in Gaza have received the first of two doses of the polio vaccine, the World Health Organization (WHO) said on Friday, after Israel’s destruction of water and sanitation systems led to a resurgence of the deadly disease in the besieged strip.

Aid workers reached more than 90% of targeted vaccine coverage in the first phase of the UN-led campaign, according to the UN’s agency for Palestine refugees, UNRWA. The second set of vaccinations is scheduled to take place in four weeks, the UN’s Office for the Coordination of Humanitarian Affairs said on Monday.

“We admire all the health teams, who conducted this complex operation,” WHO director-general, Tedros Adhanom Ghebreyesus, said in a post on X. “We are deeply grateful to the families, for their trust and cooperation.”

“This is a massive success amidst a tragic daily reality of life across the Gaza Strip. Imagine what could be achieved with a ceasefire,” he added. Israel’s offensive in Gaza, launched after the Hamas-led October 7 attacks, has precipitated a humanitarian crisis and flattened critical infrastructure. About 70% of all water and sanitation facilities have been destroyed or damaged, the WASH Cluster, a United Nations-led group that coordinates humanitarian efforts for water, sanitation and hygiene, said in July. Meanwhile, Israeli aid restrictions have severely depleted fuel stocks, chlorine and spare parts, stifling water production, purification and sewage pumping, according to the agency.

The UN’s polio campaign, facilitated by a series of pauses in fighting agreed to by Israel, came after the highly infectious virus was found in sewage samples in the strip in June. Then in August, an 11-month old boy became the first person in Gaza in 25 years to be diagnosed with polio. Polio mostly affects children under 5 years old and can cause irreversible paralysis and even death. It is highly infectious and there is no cure; it can only be prevented by immunization, according to the WHO. Relief workers described repeated challenges to the campaign rollout – especially in northern Gaza – citing Israeli evacuation orders, roads damaged by bombardment, increased hostilities and scant fuel supplies. (CNN)