The success of poliovirus vaccination represents one of the greatest milestones in the era of immunization.
Inactivated poliovirus – IPV and live oral vaccine – OPV are used for the eradication of poliovirus infection.
Inactivated poliovirus vaccine
IPV is the most preferred vaccine in the middle income countries because of the less incidence of vaccine associated paralytic poliomyelitis. IPV increases the immunity against type 1, 2 and 3 virus.
IPV is prepared by the treatment of inactivated wildtype/Sabin poliovirus with dilute formalin. It is combined with hepB vaccine, DTPa and H influenza type B vaccines in intramuscular administration. Before it was used in combination with DTPw and this practice is now found decreased as the Thimerosal in DTPw diminishes the potency of inactivated poliovirus vaccine.
Efficacy and immune response
Studies reveals that the antibody titers and seroconversion rate is more (>95%) in three dose administration in 2, 4 and 6 through 18 months of age than the schedule of 6, 10, 14 weeks. Antibodies persist for more than 5 years.
No serious adverse events are reported with IPV.
Live attenuated oral poliovirus vaccination (OPV)
Oral polio vaccine was developed from wild poliovirus in cell culture. The ease of administration, induction of mucosal immunity and low cost makes OPV an important tool in controlling the transmission of poliovirus.
Bivalent type 1 and type 3 vaccine is routinely used worldwide and has superior immunogenicity than tOPV because of the reduced interference from the type 2 virus.
OPV are no longer used in United States.
Multiple doses are required to produce an optimal immune response. Under third dose the seroconversion rates remain ≥96% and detectable antibodies remain greater than 90%even after five years.
Diarrhea in the time of oral administration of vaccine reduces the seroconversion rate.
It is found that the OPV is shed in stools and oropharynx reducing the seroconversion.
VAPP – Vaccine Associated Paralytic Poliomyelitis, is a rare consequence. People with a B cell immunodeficiency carries an increased risk of VAPP. Therefore OPV is contraindicated in immunodeficiency.
Recommend to administer bivalent vaccine at birth, 6, 10 and 14 th weeks of age and inactivated vaccine (1 dose) at ≥14 years of age.
In countries that employ only IPV, either in 3 doses – 2, 4 and 6 months of age/ 4 doses – 4, 10, 14 weeks and fourth dose at age ≥6 months.
Infants and children
Recommended schedule follows either 3 doses – 2, 4 and 6 months of age/ 4 doses – 4, 10, 14 weeks and fourth dose at age ≥6 months subcutaneously or intramuscularly.
Fourth dose is not recommended if the third dose id delayed to 4 years of age.
Special circumstances of vaccination in adults include:
- Travelers to endemic region
All long term travelers (>4 weeks) from Pakistan, Afghanistan, Syria, Nigeria and Republic of Congo should produce a valid documentation of vaccination (International Certificate of Vaccination or Prophylaxis) and ensure that a booster dose of OPV or IPV is received in 4 – 12 months prior to departure.
- Unvaccinated adults with his children receiving OPV
- Healthcare workers
- Communities at risk of wild polio virus
Dosing: 3 dose schedule – two doses of IPV at 4 to 8 weeks and third dose at 6 – 12 months.
Not recommended in pregnancy as per schedule. But, in case of increased risk vaccination is given.
Recommended in low immune patients, immunocompromised individuals and their household.