Doctors who treated former Russian spy Sergei Skripal and his daughter Yulia, who were poisoned in a nerve agent attack in March, said they are uncertain about the future of their health.
Dr Christine Blanshard, medical director at Salisbury District Hospital, told Newsnight on Monday that it was not clear whether the pair will need long-term medical assistance and care.
"I think the honest answer is that we don't know," she said. "We have a total world experience of treating three patients for the effects of Novichok poisoning and I think it's safe to say that we're still learning."
The third patient was Detective Sergeant Nick Bailey, who came into contact with the military-grade Novichok nerve agent while responding to the incident on 4 March.
Sergei Skripal was discharged from hospital this month, more than two months after he and Yulia were found slumped on a park bench in Salisbury. She was released in April and has since said she feels lucky to be alive.
Blanshard's comments came as part of a series of interviews with the staff at Salisbury District Hospital, who said that they originally did not expect the victims to survive.
"We would try all our therapies. We would ensure the best clinical care. But all the evidence was there that they would not survive," intensive care consultant Dr Stephen Jukes told Newsnight.
Their initial fears were echoed at the time by prime minister Theresa May, who warned in March the Skripals "may never recover fully".
Last week, Yulia Skripal gave a statement in which she said she and her father were extremely lucky to be alive, and that their recovery had been "slow and painful".