"I still have nightmares most nights about being completely out of my depth."
Gemma, a ward nurse in Northern Ireland, was redeployed to a critical care unit at the end of March when the first wave of coronavirus struck.
"I had never looked after a critically ill intensive care patient in my life," she says.
"I just thought, I'm coming in here and I'm going to die. I'm going to catch Covid and I'm going to be one of those patients in the beds."
As the second wave of the pandemic takes deep root across parts of the UK, thousands of NHS workers are struggling to recover from what they have already been through.
"We were all in PPE all the time," recalls Nathan, a senior intensive care nurse at a hospital in the Midlands. "All you can see is people's eyes, you can't see anything else."
He describes trying to help junior members of staff survive long and difficult days.
"And I'd see these eyes as big as saucers saying help me, do something. Make this right. Fix this."
"The pressure was insane, and the anxiety just got me," he says. "I couldn't sleep, and I couldn't eat, I was sick before work, I was shaking before I got into my car in the morning."
Nathan ended up having time off with severe anxiety, but he is now back at the hospital, waiting for the beds to fill up again.
The BBC has spoken to a number of nurses and doctors across the UK who are deeply apprehensive about what lies ahead this winter.
Source: BBC News, 24 October 2020