A five-year-old boy was left fighting for his life after developing a rare condition triggered by Covid-19.
Tracey and Robert Hanley, of Gravesend, Kent, did not think their son Marley was at risk from coronavirus.
When he ran a high temperature and got intense stomach pain they took him to hospital, assuming it was appendicitis.
But he was transferred to the Evelina Children's Hospital in London and diagnosed with Paediatric multisystem inflammatory syndrome (Pims).
Pims is caused when a child's immune system fights off coronavirus but then over-reacts to affect other parts of their body.
It occurs in less than 0.5% of children who get Covid and the symptoms are very similar to other life-threatening conditions like sepsis or meningitis.
In Marley's case, his neck swelled, his blood pressure dropped and he was left struggling to breathe.
Mrs Hanley, 31, said: "It's your worst nightmare, it's something that would never cross your mind.
"I was in a situation where I was begging a doctor to save my son's life.
"It was devastating. I wouldn't wish it on anybody."
Marley spent nearly two weeks in hospital.
He was allowed home on 9 May, but is still too weak to stand by himself.
His parents are now urging other families to be aware of the condition, and to stay vigilant as lockdown restrictions ease.
Mr Hanley, 32, said: "I nearly lost my boy, my son.
"It shows how vulnerable our children are. We need to protect them and not be complacent. The coronavirus isn't going away any time soon and we didn't know this condition even existed."
Pims was first recorded as a medical condition in April 2020 and there have been 500 cases so far in the UK.
Sara Hanna, medical director at the Evelina, said: "There is a lot of research going on to try and understand this condition better, not only to help refine the treatments that we might give in the future, but also to give us more information on how infections affect children and young people."