Why is it not necessary to give Hepatitis A vaccine to children

Why is it not necessary to give Hepatitis A vaccine to children? 

Answer: Hepatitis A, a type of jaundice is caused by a virus. This virus is transmitted through water. In many regions of India, this virus is found in drinking water. 

By the time the children reach age of five for Hepatitis A vaccination, they already have become immune to this disease. 

Therefore it is not necessary to give Hepatitis A vaccine to children.