Table of Contents
- Polio Vaccine History
- IPV Vaccine (Inactivated Polio Vaccine or Salk Vaccine)
- Oral Polio Vaccine (OPV) or Sabin Vaccine
- Polio Vaccine Schedule
- Polio Vaccine Side Effects
Polio vaccines are named after the founders; the Inactivated Polio Vaccine (IPV) is named Salk vaccine after Jonas Salk whereas the Oral Polio Vaccine (OPV) is named Sabin vaccine after Albert B. Sabin. These two vaccines are given to prevent Polio as there is currently no cure for the disease; they do this by inducing the body to produce antibodies against the poliovirus, these antibodies then neutralize the poliovirus when it enters the blood and through this prevents the spread to the central nervous system. These two vaccines contain three serotypes of the poliovirus this means that it is effective to prevent infection from serotype 1, 2 and 3 of poliovirus.
Polio Vaccine History
Jonas Salk was the first to develop a polio vaccine in 1954 using formalin to kill the poliovirus; 5 years later (in 1959), Albert Sabin developed the second polio vaccine which was an attenuated vaccine.
IPV Vaccine (Inactivated Polio Vaccine or Salk Vaccine)
The inactivated polio vaccine was developed by Jonas Salk; the vaccine is made by killing the poliovirus in formalin. This is the reason why it is known as a killed vaccine and because it has been killed, it cannot cause virulence in humans. The degree to which it will trigger immune response will be reduced compared to the weakened or attenuated oral polio vaccine.
The current version of the inactivated polio vaccine is called enhanced inactivated polio vaccine (eIPV) because it has a higher seroconversion rate and triggers the body to produce more antibodies than the earlier IPV. eIPV can also trigger mucosal immunity by inducing the production of IgA which helps it to interrupt the transmission of poliovirus but this is not as efficient as the immunity and interruption of poliovirus transmission as oral polio vaccine does; for this reason, OPV is the recommended polio vaccine in epidemics and is good for eradication of polio. IPV is best used for routine polio vaccination for prevention of occurrence. eIPV is the polio vaccine currently being manufactured and used in the United States of America while in endemic countries the monovalent oral polio vaccine is used.
Route of administration of IPV vaccine
IPV is administered in by injection into the subcutaneous tissue; this will trigger the body to produce IgG that will protect against future poliovirus infection.
Benefits of IPV vaccine
- It offers long lasting immunity more than OPV
- It cannot cause vaccine induced polio as it has been killed
- It is easier to store without being inactivated by heat
- It does not cause disease in immunosuppressed persons and can be given to those category of people
Disadvantages of IPV Vaccine
- It is administered by injection which may be unpleasant for children
- It does not stop transmission of virus except the enhanced inactivated polio vaccine version
Oral Polio Vaccine (OPV) or Sabin Vaccine
The oral polio vaccine was developed by Albert B. Sabin and was made by attenuating the poliovirus making it weak in such a way that it cannot replicate in the central nervous system but provoking the body to produce antibodies against it;
Route of administration of Oral Polio Vaccine
It is administered orally by giving 2 to 3 drops. This weakened virus can still replicate in the gut but cannot cause paralytic polio. The virus is excreted in stool but cannot cause infection in another individual.
Benefits of Oral Polio Vaccine
- OPV interrupts fecaloral transmission by causing the body to produce secretory IgA in the gut
- Children can be given the vaccine easily because it is administered through the oral route than IPV whose administration is by injection.
- OPV duration of immunity lasts longer than IPV
Disadvantages of Oral Polio Vaccine
- The weakened or attenuated poliovirus may become virulent and cause vaccine-associated paralytic poliomyelitis especially in polio type 3.
- Live attenuated oral polio vaccine is capable of causing polio in people with immunosuppression and it they should not be given OPV
- It is difficult to store OPV as it can be inactivated by heat; hence refrigeration is the best form of storage for it.
- It requires a booster vaccine to increase the duration of the immunity
Polio Vaccine Schedule
The recommended Polio vaccine schedule consists of four doses of inactivated polio vaccine (in advanced countries) that are given when the baby is 2 months old, at 4 months, at 6 to 18 months old, and the last one when the baby is about entering school at 4years to 6years of age. When an adult travels to an endemic country, a polio booster vaccine is recommended and this offers lifetime protection against poliovirus.
The polio vaccine schedule in developing countries also involves 4 doses but the oral polio vaccine is given instead of the inactivated polio vaccine because IPV is costly and also due to help prevent the spread or transmission of the poliovirus because OPV also triggers the gut to produce secretory IgA. The polio vaccine schedule in developing countries include 4 doses given at birth (or at the babys first contact with the health facility), and then at 6 weeks of age, at 10 weeks and a last dose at 14 weeks.
Polio Vaccine Side Effects
- Pain at site of injection for IPV vaccine
- Fever may occur following injection with IPV
- Vaccine associated paralytic poliomyelitis (VAPP) in rare cases of OPV, the vaccine may actually cause paralytic polio