Dr Bersin said Will had escaped “relatively unscathed”, with only a few cuts on his feet and one or two abrasions on his face and ear.
“It’s quite incredible,” he said. “Things could have been a lot worse for William with hypothermia but thankfully his temperature is OK.”
Associate Professor Joanne Grindlay from the Royal Children’s Hospital said Will had done “incredibly well” to avoid hypothermia because he probably kept moving while in the bush.
“I suspect he has kept walking around,” she said. “Children are often a lot more resilient … his age would have helped.”
Earlier, Acting Inspector Christine Lalor said Will was “alert, eating, drinking” and had asked for McDonald’s after his 46-hour ordeal.
Will could be released on Wednesday night, the doctors said.
He was reunited with his parents shortly after 1pm, in a tent at the base camp where police had set up a marshalling area to co-ordinate the search.
A short time later, he was carried into a waiting ambulance, still wearing his rescuer’s jacket, by his stepfather Nathan, his mother Penny following close behind.
From the door of the ambulance, Ms Callaghan said she was “obviously immensely relieved” and thanked the hundreds of volunteers who had searched for her son.
“He’s quite calm considering,” she said.
Ms Callaghan said Will had communicated to them that he was confused, scared and that his body felt “a bit weird”, but he was otherwise OK.
“More than anything, thank you everyone. I’m so grateful, you’re all amazing. What an amazing community,” she said.
“I want to be with my boy.”
Ms Callaghan said Will was a “very special person”, who deserved to go on a holiday after his ordeal.
“There are some amazing sides to autism. It is hard, but he’s just so special,” she said.
Volunteer Ben Gibbs, from Research, found Will standing barefoot in the bush, with his hands over his ears, blocking the noise of a helicopter above.
“I came up from the bottom of the mountain, there is a single track there I know quite well,” Mr Gibbs said.
“I just followed that up and went off track once I got near the top and saw where the guys had tagged where they searched previously and I went a bit deeper than that.”
He said it was 20 minutes from the track, relatively near the summit.
“He was really angelic, just standing there.”
Mr Gibbs said he tried to relax Will and speak calmly to him, before giving him some chocolate, socks and a jacket.
“I heard he liked Thomas the Tank Engine so I talked to him about [the character] Diesel.
“After he ate half the chocolate bar, I carried him out.”
Acting Inspector Lalor said search teams had not lost hope and that Will looked “remarkably well for the time he’s been out there”.
“[He seems like] a lovely boy, clearly a little bit overwhelmed. The fact that he’s asked for McDonald’s is a pretty good sign, I think.”
She thanked the almost 500 people in teams from the police force, SES and CFA who had been searching for Will around the clock since Monday.
“It just goes to show what can happen when everyone gets together, pulls together as a team,” she said.
Many concerned members of the public gave their time to join the effort and police were forced to turn some volunteers away.
The mood changed at the search site about 12.30pm on Wednesday as word filtered through that there had been a potential sighting of Will in the bush.
At 12.46pm, acting Inspector Lalor confirmed it was Will.
Huge grins crossed the faces of volunteers and searchers when she announced the news, as friends of the family began crying tears of relief.
Police had asked the hundreds of people waiting at the search site to be quiet and not to cheer or clap in case it spooked Will.
The teenager, who taps his chest to communicate, had spent two nights in the bush.
On Monday night, temperatures dipped toward zero degrees. The following night, the mercury dropped below 5 degrees.
On Wednesday morning, his mother described her son as a beautiful, gentle and resilient boy, and spoke of her desperate hope that he would be found safe.
“We are desperately hoping he will be found today,” she said.
“Sometimes being the mother of an autistic child is really tough. I have two boys with autism; Will is my oldest son and he would be considered very low functioning. He has an intellectual disability,” she said.
“He is very smart in his own way, I’m feeling positive as he is quite resilient. He is very skinny … but he eats all the time, he’s always on the move so he’s very fit.
“He’s such a beautiful person; he wouldn’t harm a fly and is very gentle.”
The teenager had never been camping or spent a night by himself.
Will is a fan of Thomas the Tank Engine, so three speakers moved around the area playing the program theme tune in an effort to draw him out.
Police encouraged residents to cook a barbecue as Will loves the smell of onions and bacon. He’s interested in water bottles so police asked people to put water on their verandah or porch.
They urged locals to open any windows and doors if they were cooking in the hope Will would smell the food.
with Rachel Eddie
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Simone is a crime reporter for The Age. Most recently she covered breaking news for The Age, and before that for The Australian in Melbourne.
Paul is a reporter for The Age.