A third mass polio vaccination campaign began in Gaza on Saturday, AFP journalists reported, with the aim of delivering the first dose to nearly 600,000 children across the Palestinian territory.

Scores of children under the age of 10 received the dose at a mosque in Jabalia, in northern Gaza, where a blistering Israeli military assault last year reduced many buildings to rubble.

The vaccination campaign involves multiple U.N. agencies, including the Israeli-boycotted U.N. Relief and Works Agency for Palestine refugees, or UNRWA, and comes at a time when Israel and Hamas are observing a ceasefire that has largely halted the fighting.

The United States, United Kingdom and other Western nations designate Hamas as a terror group.

The World Health Organization said the campaign aims to vaccinate more than 591,000 children by Feb. 26.

"Over 1,700 UNRWA team members will take part in this campaign," UNRWA chief Philippe Lazzarini wrote on X. "This campaign follows a recent detection of polio in wastewater, putting the lives of children at risk."

The previous two drives were conducted in late 2024 after the highly contagious disease resurfaced in Gaza for the first time in over 20 years.

After more than 16 months of war between Israel and Hamas, the humanitarian situation in Gaza is dire.

Even before the hostilities began, the territory had been struggling under an Israeli-imposed blockade for more than 15 years.

Much of the water infrastructure has been destroyed, leaving sewage to stagnate in open pools near densely populated neighborhoods — conditions that contributed to the reemergence of the virus last autumn.

The WHO reported on Feb. 19 that traces of poliovirus had again been detected in wastewater samples.

Polio is highly contagious and can cause paralysis, primarily affecting children under the age of 5. The disease has been nearly eradicated worldwide.

Hoping for a lasting truce, Bassam al-Haou, a resident of Jabalia, brought his daughters to receive the vaccine.

"I also hope for stability for our innocent children so they can remain safe from violence," he told AFP.

The war erupted following Hamas's unprecedented terror attack on Israel on Oct. 7, 2023. A fragile ceasefire took effect on Jan. 19.