However, his mother later said he was “home and he’s safe and he’s on form”.
Her son was eligible for the vaccine as his rare genetic condition means he falls within a priority group for the clinically vulnerable.
Edel Harris, chief executive of Mencap, said: “We are delighted to welcome Harvey Price as our ambassador.
“Harvey is already doing some great work to tackle online bullying and raise awareness of what life is like when you have a learning disability.
“We are pleased to be working with him to help increase the visibility of people with a learning disability across the media and society to help transform attitudes and to do our bit to ensure that the UK is the best place in the world to live for people with a learning disability.
“We look forward to unveiling our exciting plans with Harvey very soon.”
A documentary about the TV personality’s experiences of raising her son, titled Harvey And Me, aired in January.