The United Nations, in collaboration with Palestinian health authorities, began to vaccinate 640,000 children in the Gaza Strip on Sunday, with Israel and Hamas agreeing to brief pauses in their 11-month war to allow the campaign to go ahead.

The World Health Organisation (WHO) confirmed last month that a baby was partially paralysed by the type 2 polio virus, the first such case in the territory in 25 years.

The campaign began on Sunday in areas of central Gaza, and will move to other areas in coming days. Fighting will pause for at least eight hours on three consecutive days.

The WHO said the pauses will likely need to extend to a fourth day and the first round of vaccinations will take just under two weeks.

Children, escorted by members of their families, crowded a UN-run clinic in the central Gaza city of Deir Al-Balah, where around one million people were sheltering, according to Palestinian officials. Medical staffers marked children who got the drops with a pen on their fingers.

“I came to the UNRWA clinic today to vaccinate my daughters against polio and God willing we won’t see any more diseases other than the diseases we are already experiencing. I hope we will go back to our homes safe and sound," said Gaza mother Afnan Al-Muqayyad.

Polio was just one of many of Al-Muqayyad's concerns.

“Skin diseases are widespread, there are no detergents, detergents are very expensive and we can’t afford them. Also, the food is very expensive, everything is expensive, and the children’s weight is dropping, they were fine before but now they’re becoming very thin. I hope God will set things straight," she said.