Kate Garraway has revealed the reason for her husband's recent return to hospital has been "life-threatening" sepsis.
The TV presenter, 55, was back on Good Morning Britain after a three-week absence and explained why she had "dramatically disappeared" to co-host Richard Madeley.
Derek Draper, a 54-year-old former political adviser, fell seriously ill with coronavirus in March 2020 and, despite now being free of the virus, he has suffered long-lasting damage to his organs and requires daily care.
Garraway told Madeley: "I dramatically disappeared and haven't been here for three weeks now... We were on air and Derek had come out of hospital, he's been going in and out of hospital for a while for looking at ways to tackle the damage caused by Covid back in 2020.
"But we haven't really had any sort of medical eruptions, and then he just was really unwell.
"He'd come out of hospital the day before and (I) got a phone call from the person who was looking after him saying, 'right, we're really worried', so I whizzed home, and it just sort of went 'boom' from there."
Draper was taken to hospital where Garraway said they discovered he had "very severe sepsis, life-threatening sepsis".
Sepsis occurs when the body overreacts to an infection and starts to damage the body's own tissues and organs.
It can be fatal and is notoriously hard to spot.
Garraway said: "So it was really dramatic; brilliant work by the A&E, absolutely extraordinary because when you've got sepsis, the big challenge is (to) find the source of infection quickly and get the right antibiotics and his blood pressure was so low...".
She explained that by a "process of eliminations and questions", and after a junior doctor asking her what she thought the cause may be, she suggested it could be a urine infection.
Having ruled out her husband having Covid-19 again, she said: "I did wonder if it was a urine infection but weirdly, we couldn't get anything for a sample and they just went 'kidneys'?
"And it was one of those questions that was so different from all the technical, it's just like 'what was in your mind?' and I said that and it made them look at each other (and) say kidneys and unfortunately his kidneys were really badly infected, blocked.
"The challenge now is to save them, so that's where we've been for the last three weeks.
"He's still in hospital, not in intensive care, waiting for another procedure, looking really good.
"So fingers crossed on everything and particularly one kidney looking really good, just need to look at the other one, and so yeah, he's still in (a) high dependency (unit)."
Garraway added that it was "not clear yet really exactly why he's only developed this, probably due to Covid, but that's to come. The important thing is, is we're back on the right side of it now."
In an Instagram post on Sunday, ahead of her TV return, the Smooth Radio presenter had also thanked the NHS staff who had been treating Draper in intensive care, as well as fans for sending messages of support.
Last year, Garraway won a prize at the National Television Awards for the documentary Finding Derek, about her family's experience during the pandemic.
In February this year the follow-up programme titled Kate Garraway: Caring for Derek aired on ITV, and documented Draper's arrival home from the hospital while also following Garraway as she navigated the "myriad challenges of the social care system and its complexities."
The couple married in 2005 and have two children, Darcey and Billy.
Draper's battle with the virus has won much attention and support, including from Prime Minister Boris Johnson and the royal family.
