While loop that prompts for input until an integer is entered

gistfile1.txt

#This part works, it prompts the user for input, and doesn't stop prompting until there is a valid string
while [ -z "$description" ]; do
  echo -n "Please enter a description for use in the config file: "
  read description
done

#This part doesn't work, it continues to prompt whether there is a valid integer or not
while ! [[ $listID =~ '^[0-9]+$' ]]; do
  echo -n "Please enter the list ID: "
  read $listID
done