The Good Morning Britain presenter said Derek, who remains in hospital after being admitted in March, is still “ravaged” by the damage the virus has caused to his body.
During Thursday’s edition of the ITV breakfast show, Kate also opened up about how the last hellish 10 months have affected her, explaining she has been feeling “physically low” since Christmas.
“I’ve felt like I’m slightly, physically at the end of my tether. I’ve sort of had to kind of regroup a bit.”
She continued: “This week a friend of mine’s mother-in-law, who is 51, younger than me, died from Covid.
“She got it at Christmas and just went down very quickly and died.
“I just thought, I cannot believe that here we are, so far on.”
Speaking about her husband, Kate went on: “Derek is still ravaged by the effects of Covid way back in March. His recovery incredibly uncertain.
“I’m trying to look for new things and new ways and talking to doctors about what they can do for him.
“Meanwhile, people are still dying in extraordinary numbers. People that haven’t got underlying symptoms. It is unbearable.”
Earlier this week, Kate revealed she is penning a book about Derek’s battle against coronavirus, called The Power of Hope.
She told GMB viewers it has been “emotional” to write, but said: “If I can tell my story and some of the people who have helped me, then maybe that will be helpful for people.
“The book isn’t completely written, I’ve got to be honest. I’ve got about a third of it. I’m still furiously writing it. I’m struggling to get through it.
“It’s been really emotional writing it, because I’ve had to go right back to the beginning and work through.“
She added: “I don’t think I really understood what hope meant before. I used to use it very flippantly where I’d say things like, ‘Let’s hope so.’
“Hope is something very concrete and powerful, so hopefully I can share a bit of that.”
Derek was placed in an induced coma after being admitted to intensive care with coronavirus in March.
Throughout her husband’s time in hospital, Kate has candidly shared updates about his condition, as well as urging the public to take the Covid-19 pandemic seriously and follow guidelines.
In October, Kate confirmed the former lobbyist and political adviser was able to breathe without a ventilator and had mouthed his first word.
Good Morning Britain airs every weekday from 6am.