Derek Draper, the author and former political adviser, has died aged 56, his wife Kate Garraway has said.
Draper had been living with extreme complications from Covid since contracting the disease in March 2020.
TV presenter Garraway confirmed his death in a statement posted on Instagram.
"I'm sad to have to tell you all that my darling husband Derek has passed away," she wrote.
"As some of you may know he has been critically ill following a cardiac arrest in early December which, because of the damage inflicted by Covid in March 2020, led to further complications.
"Derek was surrounded by his family in his final days and I was by his side holding his hand throughout the last long hours and when he passed."
She continued: "I have so much more to say, and of course I will do so in due course, but for now I just want to thank all the medical teams who fought so hard to save him and to make his final moments as comfortable and dignified as possible.
"Sending so much love and thanks to all of you who have so generously given our family so much support. Rest gently and peacefully now Derek, my love, I was so lucky to have you in my life."
After being diagnosed with Covid, Draper was put into a coma in April 2020 and did not wake from it until the October of that year.
Despite being Covid-free by early June, his body had undergone significant damage.
After more than a year in hospital, and having still not regained his speech, Draper returned home in April 2021 on a trial basis while still receiving round-the-clock care and treatment.
In July 2022, Garraway confirmed Draper had been readmitted to hospital and later that month it was reported that his condition had worsened. He was taken to hospital in December for further treatment.
His battle with the virus won much attention and support, including from former prime minister Boris Johnson and the royal family.
The family's experience of adjusting to a new way of life due to his rare condition was chronicled in the ITV documentary Finding Derek, which went on to win a National Television Award.
ITV presenter Garraway is taking an indefinite leave of absence and has cancelled all of her TV and radio work.
Writing and Labour support
Draper, who was from Chorley in Lancashire, was a Labour Party lobbyist for almost a decade.
He left politics in 1998 after being involved in the "Lobbygate" scandal in which he was caught on record boasting of his ability to sell access to government ministers.
He retrained as a psychotherapist and wrote regularly in magazines and newspapers on psychotherapy issues. He is the author of two books, Blair's 100 Days and Life Support.
In 2009 he founded the LabourList website, a news website supportive, but independent of, the Labour Party.
He married Garraway in 2005 and they had two children together.