Image caption Simon is one of many autistic people left isolated by coronavirus

For most people the Covid-19 crisis is an unsettling, confusing time. But for hundreds of thousands of adults with autism in the UK the problems are acute.

Families and charities say this vulnerable group has been forgotten in the pandemic and they are often not receiving the care they need. Here some of them describe what things have been like since the lockdown began.

'Sick with worry'

In a few weeks Simon will be 53. He was diagnosed with autism when he was three and has been in residential care his whole life.

He has very limited communication but can say when he wants a cup of tea. In normal times, he would go riding and swimming once a week.

"He's a very active young man," says his mother Andrea. "And to me he's still a young man."

But two weeks ago Simon fell ill, with a high temperature and severe cough.

"I just felt sick with worry," Andrea says. "I mean what's going to happen to him if he is so ill he has to go into hospital?"

Despite having typical symptoms, like thousands of others, Simon has not been tested for coronavirus and Andrea is not allowed to see him.

She has nothing but praise for the care home staff but says: "No doctors will come and that is the whole problem. We don't know what we are dealing with.

"It's been terrible - probably the most stressful week in my life."

Image caption Simon's mum says he would struggle to cope if he had to be taken to hospital

Simon has no way of communicating how he's feeling, whether he's getting better or worse, and no way of processing what is happening to him.

"I can't imagine what he's thinking," Andrea says.

"Even his favourite cup of tea has disappeared because they are giving him cold drinks to keep his temperature down. He can't even say to someone, I'd really love to have a cup of tea."

Under NHS guidelines if someone with autism or a learning disability does need hospital treatment for Covid-19 then a single family member or carer can visit.

But Andrea still thinks Simon would struggle to cope.

"He would be absolutely terrified," she says. "Most hospitals have very, very limited staff who can deal with autism and learning disabilities. I just don't know what would happen."

She says Simon's condition has started to improve and he is now eating small amounts and sitting in the garden with a drink.

'What protection do I have?'

David* was diagnosed with autism and multiple learning disabilities as a child. Now in his 50s, he's spent the last 30 years living in three different residential care homes.

He is worried about what will happen if the virus spreads in the home and says people like him have been forgotten.

"Testing should be done daily on residents and care workers," he says.

"If my care workers get it or other residents get it, I'm stuck. What protection do I have? I am concerned about the lack of PPE for all care providers not just my own."

Image caption Christopher's two long-term carers have resigned, leaving him without the care he 'desperately needs'

Like many people with autism, Christopher finds it hard to handle the unpredictable.

"He gets very confused, very frustrated, with any form of change to his timetable or his daily routines," says his mother Jane. "So when situations like this arise you get a lot of anxiety from him."

Christopher lives on his own, in his own house. He has two long-term carers who help with meals, cleaning, personal care and other everyday tasks he can't do alone, but last month they both had to resign - one for health reasons, the other to look after their own children - leaving him with no support.

And because Jane lives with another vulnerable person, lockdown means she isn't able to help her son face-to-face.

"Everything has to be done within his drive, keeping the two metre distance," she says. "But that means we can't provide the personal care he desperately, desperately needs."

If - as seems likely - the lockdown continues for weeks, perhaps months, Jane fears it could be "catastrophic" for her son.

"The longer this goes on, the more anxious he's becoming, the more unconfident he's becoming, the more he's losing what we've built up with him over the years.

"He's a 40-year-old young man who has lots to give. He's an absolute treasure, but I'm so worried about this time for him."

'I'm afraid he'll lose his social skills'

Living in supported accommodation, James* has been used to receiving regular visits from his care workers.

But since the coronavirus outbreak his contact has been limited to brief phone calls or a knock at the door.

He has Asperger Syndrome and has recently been discharged from hospital where he was a patient for over 10 years.

"Gradually he's staying in more, not seeing or speaking to anyone, staying up all night and in bed for a huge part of the day," says his mother Kathy.

"I'm afraid that he's going to lose all his social skills again and get very depressed, ending up back in hospital."

Because of her age, Kathy is having to self-isolate so can only contact her son by email or video call.

"He keeps saying 'what's the point of living if we're in lockdown'.

"He's relying more and more on me for mental support rather than turning to his team. So I'm on the receiving end of the brunt of his frustrations. I'll be very glad when the lockdown is over and he can get the full support he needs."

Jane Harris, Director of External Affairs at the National Autistic Society, says "Autistic people often have communication difficulties. That means that it's harder to understand what is going on in the first place.

"But also autistic people don't often have the best support networks to start with so it's really, really hard for them to get support in a crisis, things like shopping or even just a phone call just to check that somebody is okay.

"There will be thousands of people across the country who are deeply isolated during this crisis and who need support more than ever."

The charity has published guidance for autistic people and their families to help during the pandemic. For more information on organisations that can help visit BBC Action Line.

(*names have been changed)