Today is our topic of discussion Oral polio vaccine
Oral polio vaccine
Definition:
Oral polio vaccine (OPV) is a live-attenuated vaccine, produced by the passage of the virus through non-human cells at a sub-normal temperature.
Container:
OPV is contained in vials containing 10 doses of vaccine. A single dose of oral polio vaccine is two drops. The vaccine contains small traces of neomycin and streptomycin, but no preservatives.
Immunity:
One dose of OPV produces immunity to three poliovirus serotypes in approximately 50% of recipients. Three doses of OPV produce protective antibody to all three poliovirus types in >95% of recipients.
Mechanism of immunity:
OPV produces immunity in the intestine, which is the site of entry of wild poliovirus, where the virus is endemic. The live virus in the vaccine shed in the stool and spread to others within a community, resulting in protection in individuals who are not vaccinated.
Contraindication of OPV:
Acute infectious disease, fever, diarrhoea and dysentery.
Disadvantage:
1. Chance of reversion of the vaccine virus to a virulent form.
2. The live virus has strict requirements for transport and storage, so a problem for remote areas.
Type of polio vaccine:
Inactivated (Salk) polio vaccine (IPV):
IPV is intramuscular, practiced in UK and other developed countries, where sanitary system is well developed.
Oral (Sabin) polio vaccine (OPV):
Practiced in our country due to poor sanitary system and people’s motivation.
Advantage of OPV (over IPV):
1. Easy to administer (oral)
2. More acceptable
3. No chance of immediate complications, though minor illness (e.g. fever etc) may occur.
4. Best method where there is poor sanitation system like Bangladesh.
5. Chance of development of ‘herd immunity’.
6. More effective.
7. Immunity is life long
8. Cheaper
9. Can be effectively used during epidemics 19
10. Stimulates the production of both circulatory and intestinal antibody
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