Polio Prevention - Practice and Politics
SAN FRANCISCO, December 7, 1999 -- The oral polio vaccine, a fixture of childhood immunizations since the 60's, is on its way out. Future practice will rely on plain polio shots.
This change in practice was set forth in a policy statement issued yesterday by the American Academy of Pediatrics and published in full in the December, 1999 issue of Pediatrics, the Academy's journal.
The aims of this article are to give the new policy as the Academy announced it and then to provide perspectives on it.
Press Release by American Academy of Pediatrics
The press release issued by the American Academy of Pediatrics reads as follows (verbatim):
"In an updated policy statement, the American Academy of Pediatrics (AAP) recommends that all future use of poliovirus vaccine for routine childhood immunization against poliovirus infection should be in the injected (IPV) form.
In January of 1999, recognizing the potential, albeit minimal, risk of vaccine-associated paralytic poliomyelitis (VAPP), the AAP advocated that children in the United States receive IPV for the first two doses of the polio vaccine series in most circumstances. The previous AAP statement allowed either IPV or oral poliovirus vaccine (OPV), which is given as drops, for the following two doses. However, the new policy recognizes that "VAPP can not be totally eliminated until oral poliovirus vaccine no longer is given."
"Pediatricians need to move to an all IPV schedule in an expeditious manner," said Jon Abramson, MD, FAAP, chair of the AAP Committee on Infectious Diseases. Dr. Abramson went on to say that doctors can continue to use their current supply of OPV, as long as it is administered only as the third and fourth doses. "There has never been a case of VAPP reported when the first two doses are IPV, followed by two doses of OPV," said Dr. Abramson.
Other recommendations in the policy include that, effective in early 2000, IPV is routinely given for all children at 2, 4, 6 to 18 months, and again at 4 to 6 years of age. In addition, the policy indicates that the transition to the all-IPV schedule should be completed as soon as feasible and no later than the first six months of 2000. To effect this change as soon as possible, OPV supplies no longer should be purchased for routine use.
According to the policy, OPV - if available - should be used only in the following circumstances, unless otherwise contraindicated:
- Mass vaccination campaigns to control outbreaks of paralytic poliomyelitis.
- Unvaccinated children who will be traveling in less than four weeks to areas where polio is endemic or epidemic, i.e., those for whom time before is insufficient for administration of two doses of IPV.
- During the transition to an all-IPV schedule in early 2000, remaining supplies of OPV should be preferentially used for 4-to-6- year-old children who have previously received three doses of any poliovirus vaccine to fulfill requirements for school entry. Administration of OPV to children who have previously received two doses of IPV or OPV also is acceptable.
- Children of parents who do not accept the recommended number of vaccine injections to fulfill the current childhood immunization schedule may receive OPV for the third or fourth dose. However, OPV should not be given for the first or second dose of the schedule.
- The AAP supports the World Health Organization (WHO) recommendation for use of OPV to achieve global eradication of poliomyelitis, especially in geographic areas with continued or recent circulation of wild-type poliovirus.
The statement also recommends that whenever OPV is administered, the risk of VAPP in recipients and the contacts of those recipients should be discussed with the parents or caregivers.
Medical and Historical Perspectives on the New Polio Vaccine Policy
This is the final step in phasing out the oral polio vaccine. The phaseout began in 1997 when it was recommended that the first two doses of polio vaccine be given by injection and the last two by mouth. This was instead of all four being given orally (by mouth).
The Academy alludes to "the potential, albeit minimal, risk of vaccine-associated paralytic poliomyelitis." What this refers to is the fact that the oral vaccine, which contains an attenuated (a live but weakened) form of the polio virus, can upon rare occasions cause polio, in a child receiving the vaccine or in an unvaccinated adult who comes into contact with the child. It is estimated that 8 such cases occur in the U.S. each year.
The injected vaccine cannot cause polio because it contains inactivated (dead) poliovirus.
The injected vaccine is a stronger version of the original injectable vaccine developed by Jonas Salk. The Salk vaccine was introduced to the public in 1953.
The Salk vaccine was replaced by the oral vaccine developed by Albert Sabin, The oral vaccine was more effective.
Political and Scientific Perspectives on the New Polio Vaccine Policy
The recommendation by the American Academy of Pediatrics differs in a key respect from one made in June, 1999 by the U.S. Centers for Disease Control and Prevention. The CDC recommended that doctors stop using the oral vaccine altogether in January, 2000. The Academy says it is alright for doctors to use up their leftover oral vaccine by giving it as the third or fourth dose to children who had already had two or three injections of polio vaccine.
The Academy's policy has not been universally welcomed. An advocacy group, Informed Parents Against VAPP (vaccine-associated paralytic polio) has issued a statement saying that its members were "deeply troubled" by continued use of the oral vaccine. They are concerned it may cause more cases of polio.
However, the scientific fact is that no case of polio has ever been reported in association with the oral vaccine when it is given to children who had already had two or three injected doses of polio vaccine.
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