A father has urged parents to vaccinate their children against the flu after his young daughter was left comatose with suspected brain damage after suffering from a rare complication triggered by the virus.

Gary Dunion, 41, says he feels guilty for letting vaccine hesitancy stop him from getting his children inoculated against the seasonal illness after little Sienna, 4, was diagnosed with acute necrotising encephalitis (ANE).

‘She might walk again but she might not. She might have permanent disabilities for life.

‘When we’re speaking to senior doctors and consultants, [they say] “we don’t know what this is or how it’s caused”. It’s been a really tough road.

‘She was still running around and playing and being funny until she went asleep on that Tuesday afternoon and then she woke up completely different which is mind boggling.’

ANE occurs when the body’s immune system overreacts to a common virus, like the flu.

It causes widespread inflammation and tissue damage throughout the body, including the brain, as toxins and bacteria kill tissue.

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Now Mr Dunion [pictured with Sienna] is trying to urge other parents to get their child vaccinated against the flu and raise awareness of the rare complication

Over time, the brain swells and cells die, which can cause lifelong disabilities, or even death.

Early signs of ANE include congestion, diarrhoea, fever, coughing and vomiting, but, as it progresses it can also cause severe symptoms such as fainting, loss of consciousness, difficulty with movement or coordination and seizures.

Terrifyingly, Mr Dunion, recruitment director from Corby in Northamptonshire, said that Sienna didn’t present with any stereotypical flu symptoms, and merely had a high temperature and said she was feeling run down.

He said: ‘We thought it was a common cold. We treated it with Calpol and Nurofen. It’s honestly insane.

‘It’s just a complete shock.

‘I’d never heard of [ANE] before in my life. They said it’s a very, very rare but aggressive brain condition triggered either by the flu or Covid-19.’

The Dunion family’s nightmare began on November 16 after Mr Dunion and his wife Angelina, 38, surprised Sienna and her sister Ariana, 7, with tickets to a Christmas theme park.

Mr Dunion said: ‘We’d literally just given our girls Lapland UK tickets and pretended they came from the North Pole and put them in the freezer and they were really cold.

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Initially, Sienna’s [pictured] parents thought she was just joking when she said she felt cold

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Her parents had given their two daughters, Sienna (at the back) and her sister Ariana, 7, (at the front) tickets to Lapland which they’d hidden in the freezer

‘Sienna said “Dad I’m really cold, I feel really chilly, maybe it’s from the North Pole”. And we thought “maybe she’s just knocking around”.’

But just a couple of days later, in every parent’s worst nightmare, he found Sienna unconscious, prompting a rush to hospital.

There, once she had been put on a drip, doctors noticed her fingers had started clawing—an involuntary movement—prompting them to order a CT scan.

It revealed anomalies on her brain, and when she became unresponsive, medics placed her in an induced coma and transferred her to a different hospital for specialist care.

Sienna began a course of treatment called plasma exchange—a blood purification therapy—but she had to have emergency surgery after doctors discovered she had abnormally high lactate levels, a sign that ANE has progressed.

They discovered 60 per cent of her intestines were damaged beyond repair and needed to be removed; she subsequently needed a second surgery to release air that had begun collecting in her abdomen.

Now her father is wrestling with the guilt of not getting her vaccinated.

He said: ‘We didn’t give her the flu jab and the biggest message for me to parents is to vaccinate your children with the flu.

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Sienna began plasma exchange, a blood purification therapy, but she also had to have emergency surgery

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At the hospital doctors put her in a coma after a CT scan revealed abnormalities on her brain

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Her father fears he will never be able to hear his child’s ‘infectious belly laugh’ again

‘It doesn’t eradicate you from getting this, but we didn’t give her it because we’d heard horrendous stories.

‘There’s been a lot of trepidation around the Covid vaccination and people are quite wary about what they’re putting into their children, and I think that’s impacted us certainly.

‘The guilt from us is like “my god, should we have vaccinated her”. So many parents out there just aren’t doing it because they are unsure what they’re going to do or if they are really going to need it.’

As cases of the ‘mutant flu’ sweep Britain, health chiefs have urged those eligible for the free NHS vaccine, including children, over 65s and people with some conditions, to get their free jab from their GP or local pharmacy.

Recalling how their lives changed, almost overnight, Mr Dunion said: ‘I took her out on a scooter ride and for the first time ever she lasted about five minutes, and she was freezing and wanted to come back home so we did.

‘On Sunday night she had a temperature, but it was nothing concerning. It was manageable with Calpol, and we kept her off school on the Monday and she was playing with Barbies.

‘On Tuesday at about 4pm she took a nap on the sofa, and we just thought she was absolutely exhausted.

‘On Wednesday morning I took our eldest to school and I got back at 9am and my wife said, “something’s not right with Sienna, she’s not conscious or answering any questions”.’

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Her father says Sienna [pictured] showed no signs of the flu other than a slight temperature and the fact she’d been a bit run down

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Her parents have been told doctors don’t know when she will wake up, and if she will be able to walk, talk or eat

Now he fears he might never hear his child’s ‘infectious belly laugh’ again as it is unknown when, or if, she will wake up and if she’ll ever be able to walk, talk, or eat unaided.

‘Now reality has set in. It just feels so unfair on Sienna, who’s the most beautiful girl,’ he said.

‘We don’t understand why this has happened. There’s no rhyme or reason when she’s one of a handful of people globally who’s ever had this.

‘It’s been horrendous and I can’t comprehend how a really funny, caring, healthy four-year-old three weeks ago just to this and potentially may never recover.’

The father now wants to warn other parents and spread awareness of the condition.

He said: ‘There’s so much determination from me now. She’s been fighting from hell so it’s my turn now to stand up for her.

‘For me it’s raising awareness around ANE and what it is. No one is immune from it even though it’s absolutely very rare.

‘There needs to be some serious medical studies around what the factors are that trigger it. Beyond that, what’s the treatment and the early interventions, what’s the recovery from this and what’s the prognosis. It’s so much guess work.

‘It creates a response in the immune system where the immune system does not recognise the danger, and the virus keeps on attaching itself to the brain and it doesn’t fix itself or try to fight it and then attaches itself to the spine.’

Mr Dunion is also doing a fundraiser which he hopes will help to support his daughter’s future treatment and send her to a neurorehabilitation centre which costs around £8,000 a week.

‘As a person and a dad, any issues my girls have I deal with and I fix it. With this I’m just so out of control, I can’t do a thing but be there next to her holding her hand,’ he said.

‘Raising awareness and funds giving her the best chance is my way of trying to do something for her.

‘We’re not quite sure where we’re going to land with her at all. We’re doing a lot of research in terms of giving her the best care for whenever we eventually are discharged from here.

‘There’s no rhyme or reason why children get this or how it’s caused. The biggest thing is there’s no real prognosis and the treatment isn’t standard.’