Does herpangina requires antibiotics for 2 years old or 9 months child ?

Actually no.: Herpangina is caused by herpes virus--hence the name. As you may be aware viruses do not respond to antibiotics--only bacteria are affected by antibiotics. Usually with reasonable oral hygiene our own immune system should be able to manage this viral infection. However, with limited special situations, your pediatrician may prescribe the antiviral acyclovir. It must be begun in the first 1-2 days.