The people transported out of Gaza in the medical evacuation operation will be taken to the United Arab Emirates or Romania for treatment.
One of those being moved was Khuloud Tabasi's son Mohammed.
Hugging her husband as she entered the ambulance in the southern city of Khan Younis, Khuloud said after four operations her son’s “situation went from bad to worse... Thank God [the WHO] organised the evacuation of my son."
Israel has been under growing international pressure to do something to improve the humanitarian situation in the Gaza Strip.
Last weekend, 15 senior UN figures said conditions in the north were “apocalyptic”, with the entire population “at risk of death from starvation, disease and violence”.
Israel has also faced calls from its ally, the US, to take action. Secretary of State Antony Blinken warned the Israeli government on 13 October that it had 30 days to “surge” humanitarian aid to Gaza or risk having some US military assistance cut off.
The numbers still in need of medical support are huge, with 19 out of Gaza's 36 hospitals out of service and the other 17 only partially functional.
Dr Marwan Abu Saada is general manager of the al-Shifa medical complex in Gaza City, which was left in ruins after being raided by Israeli forces for a second time in March.
The IDF said it had been used by Hamas for military purposes, something the group has always denied.
Parts of al-Shifa have now been rebuilt and reopened, including the emergency department, and the hospital recently received patients evacuated from hospitals in Beit Lahia.
Dr Abu Saada said there were children with leukaemia, people with breast and other cancers, as well as those disabled by the fighting.
“They desperately need to travel abroad as soon as possible,” he said. "Since none of the treatment facilities are available in Gaza.”
While Wednesday’s evacuation has been widely welcomed, the numbers taken to the UAE and Romania are a small fraction of the total who need medical aid.
More than that, as long as the fighting continues, the numbers in need of help will continue to grow.