A fit and healthy 42-year-old who loved climbing mountains and lifting weights has died of Covid after refusing to get the vaccine, leaving his twin sister and mother heartbroken and warning others not to think they are invulnerable to the dangers of the virus.

The father of one, John Eyers, a construction expert from Southport in Merseyside, was described by his sister Jenny McCann as “the fittest, healthiest person I know”.

She added that her brother had been climbing Welsh mountains and wild camping four weeks before his death.

But he was left in intensive care after catching coronavirus, telling his consultant before he was ventilated that he wished he had been vaccinated. His twin said her brother’s death was “a tragedy”.

“He thought if he contracted Covid-19 he would be OK. He thought he would have a mild illness. He didn’t want to put a vaccine on his body. His was pumped full of every drug in the hospital. They threw everything at him,” McCann said on Twitter.

“It should not have happened. He leaves a mum and a dad, a sister (me), and a 19-year-old daughter. My two children have lost their fun uncle. The uncle who would always play with them.”

McCann said her brother had dressed up as Father Christmas for her children. “My mum has lost her baby boy. My niece, her much loved and needed dad. This shouldn’t have happened. My mum wants people to know about John. For his story to save someone’s life. For the pain and loss to drive people to get a vaccine.”

Tributes also poured in from Eyers’ friends, with many describing him as “an incredibly fit person” and “one of the most active and fit people” they knew.

One friend wrote: “He had a huge love for sport and fitness competing in bodybuilding, triathlons, rock climbing and much more.

“He helped me a few years back when I was competing as I was struggling with my prep and he was the support and extra guidance I needed to push me through my show.

“He wasn’t my coach. He helped me in his spare time and from the goodness of his heart, as fitness was such a huge passion of his. I can never thank him enough for his support.”

He added: “John sadly was lost to Covid without any underlying health conditions. His family wants this sharing for others to see and make them re-think some of their decisions surrounding Covid, which I think is absolutely incredible.”

Healthcare workers and Covid patients have increasingly spoken out about feeling a sense of regret about being unvaccinated once they fall seriously ill.

Dr Samantha Batt-Rawden, a senior intensive care registrar, said she had come across only one patient in critical care who had received both vaccination doses, and that the “vast majority” of people she was seeing were “completely unvaccinated”.

Batt-Rawden said it was difficult to witness the look of regret on patients’ faces when they became unwell and needed to go on a ventilator. “You can see it dawn on them that they potentially made the biggest mistake of their lives [in not getting the vaccine], which is really hard,” she said, adding that she had overheard people telling family members about their remorse.