Hadassah Medical Centre described Mr Erekat’s case as extremely challenging given his history of health problems, including a lung transplant performed three years ago.
It said he suffered from a weak immune system and a bacterial infection in addition to Covid-19.
It added Mr Erekat, 65, was sedated and that its most senior doctors were consulting with international experts on how best to manage such a complicated case.
Mr Erekat has been one of the Palestinians’ most recognisable faces over the past 30 years, serving as their senior negotiator during on-again, off-again peace talks.
He was also a top aide to late Palestinian leader Yasser Arafat and current Palestinian President Mahmoud Abbas.
A fluent English speaker, Western-educated Mr Erekat also makes frequent appearances in the media.
He was transferred to Hadassah on Sunday at the request of the Palestinian Authority.
