Hello, Thnx to contact us. If I am your treating doctor I would like to advice you that vaccination does not cause rise in eosinophil count. Common cause of eosinophilia include allergy and parasitic infection. Try to find out this two causes from your son. There are other rare causes of eosionphilia also there but they are very rare this include: polyarteritis nodosa, Churg-Strauss syndrome Addison s disease, skin disease - pemphigus, urticaria, eczema, dermatitis herpetiformis, erythema multiforme; Loeffler s syndrome, Loeffler s endocarditis, scarlet fever, irradiation, during convalescence from any infection, hypereosinophilic syndrome, post-splenectomy, cholesterol emboli syndrome, drugs - penicillins, streptomycin. If you have anything else to ask please contact me. Thanx. Dr. Arun Tank