IPV /salk polio vaccine. Strains - Mahoney( salk type 1) MEF1( salk type 2) saukett( salk type 3) Inactivated in formaldehyde. Final vaccine mixture contains 40 units of type1, 8 units of type 2, and 32 units of type3. Administration- intramuscular injection or subcutaneous. Should be refrigerated to ensure no loss of potency. Freezing avoided. Either administered alone or in combination with other vaccine antigens including diphtheria,tetanus,whole cell or acellular peussis,Hepatitis B, or Haemophilus influenza type b. Primary/initial course consists of 4 inoculation: first 3doses given at an interval of 1-2 months and 4 th dose 6-12 months after 3 rd dose. First dose given when the infant is 6 weeks old. Additional doses recommended prior to school entry and then every 5 yrs until the age of 18. Alternatively one/two doses of OPV can be safely given as boosters after an initial course of immunisation with inactivated vaccine. Immunity:- induces circulating humoral antibodies(IgM,IgG,IgA). Doesn&;t induce intestinal or local immunity. The circulating antibodies protect the individual against paralytic polio,but do not prevent reinfection of gut by wild viruses. In case of epidemic, IPV is unsustainable because immunity is not rapidly achieved as more than one dose required to induce immunity and injections are to be avoided during epidemic as they are likely to precipitate paralysis. Advantages:- it doesn&;t contain living virus ,so safe to administer : 1. To persons with immunodeficiency diseases. 2. To persons undergoing coicosteroid and radiation therapy. 3. To those over 50 years who are receiving vaccine for first time. 4. During pregnancy. 5. IPV is an alternative to OPV for immunisation of children with HIV infection. No serious adverse effects noticed {Reference: park&;s textbook of preventive and social medicine, 23rd edition, pg no.206 }