On Thursday, the United Nations announced a plan to try to address one of the most terrifying consequences of Israels U.S.-backed offensive war in the Gaza Strip: the return of the feared poliovirus to the Palestinian territory.

Health experts call the U.N. campaign a hugely important bid to protect hundreds of thousands of children in Gaza and to shield neighboring communities but they are unsure whether it will work, as fighting between Israel and Gaza-based militant group Hamas continues.

Polio had been wiped out in Gaza as it has in much of the world, with its last case reported 25 years ago. Yet Israels military operation, which followed a Hamas-led attack on Israel in October 2023, destroyed the areas water and medical facilities and forced nearly 2 million people out of their homes. This created conditions in which the virus could flourish.

Earlier this month, local health officials confirmed that a baby had contracted the disease. The child, 11-month-old Abdul Rahman, has become severely weak, his mother recently told CNN ; polio cannot be cured and can lead to paralysis or death for children.

Starting Sunday, medical personnel working with the U.N., partner organizations and Gazas Health Ministry will attempt to provide polio vaccines to an estimated 640,000 children in the strip who are under the age of 10, said Dr. Rik Peeperkorn of the United Nations World Health Organization in a Thursday press conference.

U.N. negotiations with Israeli authorities over the vaccination campaign failed to achieve the goal that aid groups sought: a polio pause in combat across Gaza, an idea that Hamas agreed to but was a tougher sell to Israels hawkish government. Instead, three-day, area-specific pauses to allow for the safe delivery of vaccinations will occur in different sections of the territory, Peeperkorn said, starting in central Gaza, where Israeli evacuation orders covering other parts of the strip have forced more than an estimated 1 million people onto a tiny piece of land.

For humanitarian workers who have already spent nearly 11 months trying to support people in Gaza, the painful process of reaching a deal was noteworthy in itself given the danger that polio poses.

Its really important that people understand the craziness of this, the depravity. Polios been almost eradicated in the world, said Sean Carroll, the CEO of the aid group Anera.

The idea that wed be debating whether theres a cease-fire to deliver polio vaccines this is crazy, continued Carroll, a former official at the U.S. Agency for International Development.

The sentiment reflects a concern that aid groups have expressed since the start of the war, particularly in calling for a different approach from Washington, the main sponsor of Israels military operation. To a degree not seen in other conflicts, including past Israeli-Palestinian clashes, they say the U.S. and other world powers are missing the forest for the trees. Amid Israels sweeping operation, officials are discussing details like how many trucks full of aid enter Gaza or how many days Israel will halt fighting to deliver vaccines instead of big steps that could dramatically ease Palestinian suffering, like Israel restoring electricity to the territory, ceasing its practice of forcing mass displacement, or adopting an immediate cease-fire.