POLIO VACCINATION

POLIO VACCINATION

Oral polio vaccine (OPV), Sabin vaccine, is at live but attenuated virus. Storage is best done at 2 to 10 degree C. Since it is cheaper, easy to administer, helps to prevent establishment and spread of wild pathogenic poliovirus in the community, and can be used in blanketing operation to check the spread of an incipient outbreak, it is being used by large majority of the countries the world over. This has earned it the designation “community vaccine”.

The killed (inactivated) injectable polio vaccine (IPV), the so called Salk vaccine, is required to be administrated parenterally. It does not interfere with the speed of natural virus in the community though it does produce individual immunity to polio.

Both vaccines, usually supplied as a trivalent antigen providing three strains of poliovirus(Lansing, Leon and Brunhide), are highly effective. Monovalent OPV, providing only one strain, is also available (mOPV).

Age to vaccinate

 Primary doses are given at birth (zero dose), then at 6 weeks, 10 weeks, and 14 weeks. A booster dose is given in second year (15-18) months and yet another in the fifth year. A total of 6 doses are, therefore, recommended to ensure reasonably high personal protection from polio-myelitis.

OPV given in pulse polio campaigns should be considered over and above these doses. OPV requires to be essentially administrated even if the child has suffered from the disease.

In grown-up children (beyond 8 years of age) polio vaccine may not given. This is because the older children are more or less immune to natural infection with poliovirus.

Administration

 OPV is administrated as two drops directly into the mouth. This should be followed with the feeding of some water to ensure absolute ingestion of the vaccine. It is now convincingly shown that antibodies in breast milk against poliomyelitis do not interfere with the take of the vaccine and the consequent immune response. Breastfeeding need not be skipped before and after OPV administration.

Pulse polio means simultaneous mass immunization of all infants and children 5 years at a particular date i.e National Immunization Day (NID) during winter (usually Dec-Jan) regardless of their immunization status. It is over and above the routine doses OPV.

Mopping-up means administration of OPV, in two doses 4-6 week apart, to all children under 5 years regardless of their immunization status in areas at high-risk for transmission of wild polio virus. For this purpose, house-to-house visits are made in the concerned area.

Ring immunization means administration of OPV, in two doses 4-6 week apart, to all children under 5 years within an area of 5 km within 48 hours of finding a case of polio.

OPV behaves in the body

On entry in the gut, strains of OPV multiply. As a result there is production of local as well as systemic immunity. The vaccine also leads to production of antibodies like IgG, IgM and IgA. The last-named is said to contribute to the local immunity whereas the remaining two limit spread of the poliovirus to the CNS and protect against paralysis.

Contraindications

1. It should be avoided in children suffering from severe diarrhea and an acute illness.

2. Leukemia and other malignancies

3. HIV (immunocompromised state, symptomatic)

Adverse reactions

Though OPV is exceedingly safe, it may cause.

1. Mild diarrhea in case of overdose.
2. Vaccine-associated paralytic poliomyelitis(VAPP) due to vaccine virus per se very rare(one in 2.5 millions).
3. Monitoring  : If the inner square of the vial matches the outer square or becomes darker , the vaccine should be discarded.

Enhanced inactivated polio vaccine (EIPV)(SALK VACCINE)

 Now that eradication of polio is round the corner, over and above the OPV, the enhanced IPV (available as imovax polio) my be introduced in the national immunization schedule. In addition to routine immunization against polio. It is especially indicated in immunocompromised children and for boosting the eradication endeavors.

Dosage Schedule

1. 0.5 ml(SC) in lateral thigh in infants and deltoid in grown-up children at

-          8 and 16 weeks, or

-          6,10 and 14 weeks

2. Booster is required at 15 months.

Side-effects

No significant side-effects

Storage

2-8 degree C

Availability

As such and in combination with other vaccines.