The polio vaccine protects children from 3 types of polio viruses that are associated with childhood paralysis. Poliomyelitis is a disease that affects the nervous system and can lead to paralysis of the extremities and dysfunction in motor control.
The polio vaccine can be taken in an oral form (OPV) or injectable form (IPV), and is usually given in 3 doses during infancy, with a fourth booster dose given in later childhood. The oral form is made up of a weakened, live polio virus that stimulates an immune response to make antibodies, while the injectable is composed of inactivated strains of the virus.
The WHO recommends that the first two doses are given prior to 6 months of age, and that the last two are given prior to 5 years.
Immunization schedule
The WHO recommends that vaccination against polio should start at 2 months of age and end before the child turns five. However, interrupted vaccine schedules can continue in adulthood. There are slight variations between the vaccine schedules in USA, Canada and England, which can be observed in the following table:
| USA | Canada | England | |
|---|---|---|---|
| First dose | 2 months | 2 months | 8 weeks |
| Second dose | 4 months | 4 months | 12 weeks |
| Third dose | 6 months | 6 months | 16 weeks |
| Booster dose | 4 to 6 years old | 18 months | 3 years old |
Although the oral form of the vaccine is a less invasive immunization method and is associated with higher rates of intestinal immunity, the injectable form is the preferred method of administration. OPV poses a minimal risk of OPV-associated paralytic polio as an adverse effect of vaccination, making IPV a safer option. Many countries, like Canada and USA, have exclusively administered IPV as of 1995.
How to prepare for vaccination
Administration of IPV does not require any special preparation. Babies who will be taking OPV are advised to hold off on any feeds 1 hour prior, to prevent any possible spitting-up of the vaccine. If the baby vomits or spits-up following the oral vaccine, a new dose is advised to ensure full immunization.
Contraindications for vaccination
The polio vaccine should not be administered to children with an immune system weakened by illnesses like AIDS, cancer or post-organ transplant. This population should be assessed on a case-by-case basis, and should following vaccination schedules as indicated by their pediatrician.
Vaccinations should be delayed if the child is ill on the day of administration, particularly if they have vomiting or diarrhea. These symptoms can interfere the vaccine absorption. Children with a history of polio should also be exempt from vaccination.
Possible side effects
The polio vaccine rarely causes with any side-effects, though some children may experience fever, general malaise, diarrhea or headache following vaccination. If the child shows signs of paralysis, which is an extremely rare side-effect, urgent medical attention is strongly advised.
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