Ratio of virus type 1:2:3 subtypes in vaccine shown in photograph:
Vaccine shown is oral polio Vaccine Sabin.
Inactivated polio (Salk) vaccine
- IPV induces humoral immunity (IgM, IgG and IgA in the serum).
- Circulating antibodies protect the individual against paralytic polio, but do not prevent reinfection of the gut by wild viruses because IPV does not induce local intestinal immunity –
- Vaccine contains all the three types of poliovirus, inactivated by formalin, i.e. killed vaccine.
- It contains 40, 8 and 32 D antigen units of type 1, 2 and 3 virus respectively (Previous vaccine had 20, 2 and 4 D antigens, according to 20th/e of Park).
- The primary or initial course of immunization consists of 4 inoculation (4 doses).
- The first 3 doses are given at intervals of 1-2 months and 4′ dose 6-12 months after the third dose.
- First dose usually given when the infant is 6 weeks old.
- Additional doses are recommended prior to school entry and then every 5 years until the age of 18.
- Being an inactivated vaccine, it can be given to immunosuppressed individuals, e.g. AIDS patients.
- IPV is administered by IM injection (preferred) or subcutaneous injection.
- It can be combined with DPT, Hepatitis, and/or H. influenzae type B vaccine. In the combination vaccines, the alum or the pertussis vaccine, or both have an adjuvant effect.
- In regions without wild poliovirus, inactivated polio vaccine is the vaccine of choice.
- IPV is not recommended for control of epidemics.
Oral (sabin) polio vaccine
- It is mostly used in India (Routine immunizations, as well as pulse polio immunization).
- Useful in controlling epidemics.
- Relatively inexpensive.
- OPV induces local intestinal immunity by production of secretory IgA as well as humoral immunity by inducing production of serum antibodies (IgG). So, it gives protection from paralysis and also prevents infection of the gut by wild viruses.
- In OPV, the viruses multiply in the gut and the vaccine progency is excreted in the feces and secondary spread occurs to house hold contacts and susceptible contacts in the community.
- Non-immunized person may therefore, be immunized.
- Thus widespread herd immunity results, even if only approximately 66% of the community is immunized (100% coverage is not required).
- It contains live attenuated viruss (type 1, 2 and 3) grown in primary monkey kidney or human diploid cell culture.
- The vaccine contains :-
- i) Over 300,000 TCID 50 of type 1 poliovirus
- ii) Over 100,000 TCID 50 of type 2 poliovirus
- iii) Over 300,000 TCID 50 of type 3 poliovirus o Dose 2 drop (0.1 ml)
- Schedule in National Immunization Programme of India.
- OPV-0 (Zero dose) At birth
- OPV-1 6 weeks
- OPV-2 10 weeks
- OPV-3 14 weeks
- OPV-B (Booster dose) 16-24 months
- OPV is a thermolabile vaccine -p maintenance of cold chian is required and vaccine is stored at -20°C in deep freeze.