David Aibuki looks like any normal, healthy, happy five-year-old boy. He is a bit shy when we first meet but soon warms up when I start talking about Christmas.
His little brown eyes light up when he tells me he's asked Santa to bring him a gold racing car for his present this year.
I ask David if he's been a good boy to earn his present and he replies "Yes!"
His smile fills the room.
I don't know if David has been good. But I do know he's been extremely brave.
He is sitting on a bed in a specialist children's ward at St Mary's Hospital in Paddington. David was taken here two weeks ago and admitted to the hospital's PICU (paediatric intensive care unit) during what his mother describes as a "terrifying" ordeal.
David has sickle cell disease. His mother Bola Aibuki monitors him very closely and when he told her he was in excruciating pain, saying his "bones were broken", she knew his little body was under attack.
She took him to her local hospital where doctors diagnosed the flu. That meant that with his underlying health conditions David was in excruciating pain and his health was under serious threat.
"David would never tell if he's in pain, I would just assume that he's in pain. But once David said my bone is cracking I definitely knew something was not right with him," Bola told me.
Managing David's condition can be difficult at the best of times but the added infection was making David very sick. It was an agonising time for his family.
Bola described her fear to me: "It was terrifying, I can't even hold back. I was trying, the nurses were really trying their best to distract me but just me looking at my own son lying there, helpless. It's just too much really for any mum to go through."
Shortage of beds
The doctors at West Middlesex University Hospital turned to the specialist paediatric care team at St Mary's for their expertise.
David was put under the care of Dr Liz Whittaker. She recognised immediately the complexity of David's case and proceeded with an urgent blood transfusion to help David's body fight the infection.
"We have lots and lots of children coming in, they're all quite sick, there is a shortage of beds," Dr Whittaker explained.
"We are always worried about flow, we're trying to keep everyone moving through the system so every child can get the care they need. We've set up community treatment to make sure we have access to get patients out of hospital.
"But November is always a stress point and anything we can do to try and limit how many patients there are is a really good thing."
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'Paediatric winter' under way
Children's doctors say "paediatric winter" is well under way. November is usually when RSV (respiratory syncytial virus) cases spike.
They are seeing this in hospitals already. And once RSV cases decline, flu starts to pick up. So there is no let-up for medics like Dr Whittaker and her team.
Senior paediatricians have told me there is an acute shortage of PICU beds, especially in the south of the country.
Dr Whittaker said in her hospital it was "one patient out and one patient in". Data from NHS England seems to show there were as few as 33 spare PICU beds available in the country last Thursday. That is less than at any point last winter.
Health analysts say this rise in winter respiratory cases was to be expected. Mitigating measures during the pandemic meant flu and RSV did not have a chance to spread as they normally do. But it also means that most young children have not been exposed to these viruses before.
David is recovering well and looking forward to going home to spend Christmas with his family and look forward to his gold racing car.
But Dr Whittaker and her team know David's bed will not be empty for long.