In reply to wurzelinzummerset:
Sounds like a pretty simple break. I'd remove the cast at home.
Taking into account what two_tapirs said, you should be able to work out the size of tubigrip required and order one from the internet.
Do a bit of very gentle experimental movement to see if he/she still has the normal range of movement.
Moving forward, build up use of that hand only very slowly to minimise chances of a re-break if it wasn't healed up enough and should have had another cast put on it.
It's a hard call to make with both Corona and a re-break with further complications (e.g. damage to the wrist arteries) are very worrying risks.