"We are pleased to announce that UNRWA has secured the formal authorization for the transfer of 10,000 polio vaccines to Yarmouk," UNRWA spokesman Chris Gunness said Wednesday.
"This process has been completed without incident and the vaccination of thousands of children in the camp is now under way."
Gunness said food distributions that began on January 18, haltingly at first before picking up speed in recent days, continued on Wednesday.
He said 5,194 food parcels had been distributed to the camp since UNRWA gained access.
Once home to some 150,000 Palestinians, as well as Syrians, Yarmouk has been devastated by the fighting, and now just 18,000 civilians are believed to remain inside.
More than 130,000 people have been killed since the foreign-backed insurgency against President Bashar al-Assad began in March 2011, and millions more have been displaced in what UN officials have described as the worst refugee crisis in two decades.
HH/MB