Answer:
Dear brother,
You know that there's another virus going around the world, and do you want to stop it from coming near us?
Follow my rules, wash your hand everyday, and after every twenty minutes. Do not shake hands or do closed interaction with anyone, stay hydrated to prevent sore throat and do not touch your face( eyes, ears nose and mouth).Always brush your teeth everyday, and night. And take showers/bath everyday ( if it's a summer) or after every 2days.
Lots of love,
Your big sister.