Flu vaccine will help . But it has to be given around the months of July and august before the season starts. Since the Flu or common cold is a viral infection and every year the strain of the infection can change! Pnemovac comes with 23 strains of virus and it helps to over come the infection caused with these strains. Children who are having enlarged tonsils and adenoids can also suffer with the same symptoms your child is having. A visit to an ENT surgeon to rule out the tonsils and adenoids will help. If your child is sleeping with mouth open and snores in the sleep then definitely take an ENT opinion.