Rebuilding Gaza's shattered health system is expected to require at least $10 billion over the next five to seven years, according to an initial assessment by the World Health Organization released Thursday.
"The needs are massive," the U.N. health agency's representative in the Palestinian territories, Rik Peeperkorn, told reporters.
With a cease-fire finally looming, humanitarians are calling for a dramatic scaling up of humanitarian aid into war-ravaged Gaza amid efforts to determine the size of the towering needs.
Peeperkorn said his team's initial estimate of the cost to rebuild just the health sector was "even more than $3 billion for the first 1.5 years and then actually $10 billion for the five to seven years."
"In Gaza, we all know the destruction is so massive. I have never seen that anywhere else in my life," he said.
WHO chief Tedros Adhanom Ghebreyesus meanwhile said "less than half of Gaza hospitals are functional."
He hailed Wednesday's announcement from mediators that Israel and Hamas had finally reached a truce as "just about the best news."
He voiced hope that "this agreement marks the end of the darkest chapter in the history of the relationship between the Israelis and the Palestinians."
"We welcome this news with great relief, but also with sorrow that it has come too late for those who have died in the conflict," Tedros said.
He also voiced "caution, given that we have had false dawns before, and the deal has not yet been confirmed."
While the mediators said the deal was due to take effect on Sunday, Tedros urged the sides not to wait. The fragile deal still has to be approved by Israel's cabinet.
Over 15 months of deadly Israeli attacks on the Gaza Strip killed nearly 46,800 people, mostly women and children, and injured over 110,000 others.
"If both sides are committed to a cease-fire, it should start immediately," Tedros said. "The best medicine is peace."
"So, let the healing begin, not just for Gaza, but for Israel as well. This is in everyone's best interest."
Peeperkorn said the WHO stood ready to "expand its support rapidly" in the territory.
"What is critical though is that the significant security the political obstacles to delivering aid across Gaza are removed," he said.
"We need a rapid, unhindered and safe access to expedite the flow of aid into and across Gaza."
