A polio vaccination campaign began Sunday in war-ravaged Gaza, with humanitarian pauses announced by the United Nations to allow for large-scale inoculation.

The campaign was announced after Gaza recorded its first polio case in a quarter of a century last month.

It officially began on Sunday in three health centers in central Gaza, a day after an unspecified number of children were vaccinated in the southern area of the Gaza Strip.

Children aged from 1 day old to 10 years arrived at the centers to receive the dose as drones flew overhead, said Yasser Shaabane, medical director of Al-Awda hospital in central Gaza said.

"There are a lot of drones flying over central Gaza and we hope this vaccination campaign for children will be calm," said Shaabane.

The campaign began at 9 a.m. (6 a.m. GMT), he said.

The World Health Organization (WHO) said Thursday that Israel had agreed to a series of three-day "humanitarian pauses" in northern, southern and central areas to facilitate vaccinations.

Israeli Prime Minister Benjamin Netanyahu, however, has insisted that these pauses were not amounting to any cease-fire in overall fighting in Gaza.

The campaign aims to vaccinate more than 640,000 children in the besieged Palestinian territory, devastated by almost 11 months of Israel's genocidal war.

The campaign also aims to administer the first dose – two drops – to at least 90% of the territory's children.

Polio, which had been eradicated in Gaza for 25 years, reappeared amid the conflict that was triggered by the Oct. 7 Hamas incursion of southern Israel.

WHO has despatched 1.26 million doses of the oral vaccine to Gaza already.

The health ministry in Hamas-run Gaza has identified 67 vaccination centers – mostly hospitals, smaller health centers and schools – in central Gaza, 59 in southern Gaza and 33 in northern Gaza to administer the doses.

The second dose of the vaccine must be given four weeks after the first.