This post is a continuation of a series that will be providing information on each disease and vaccine that is currently on the CDC’s recommended national immunization schedule. I hope this information is able to help those attempting to decide on an alternative vaccine schedule (whether that is a delay, select or decline one). Please leave a comment if you have any questions.
The information below is gathered from sources included PubMed, the CDC, the Mayo Clinic, and package inserts published from the vaccine manufacturer. (See below for a full list) Be sure to check out the other posts on this series (Hepatitis B and Rotavirus).
The Disease
Polio or Poliomyelitis is derived from two Greek words: polio (grey) and myelon (marrow of the spinal cord). This name illustrates the effect poliomyelitis virus has on the spinal cord which leads to the characteristic paralysis we all associate with the disease. Interestingly, 95% of polio infection is subclinical meaning that the virus causes no symptoms.
The poliovirus is a member of the enterovirus subgroup which means that it has the ability to multiply in the gastrointestinal tract and is stable at an acid pH.
Humans are the only known reservoir for the virus.
Prevalence
At one point, transmission of poliovirus infection occurred around the globe. It has now been declared eradicated in the western hemisphere. Currently Pakistan, Afghanistan and Nigeria are the only countries where poliovirus is labeled as endemic (living within a geographical area).
It is known that the ecology and herd immunity characteristics of polioviruses are heavily dependent upon levels of hygiene (pg 290). The poliovirus will mainly infect children under 5 years old and populations living in socioeconomically disadvantaged areas, where sanitation is poor and access to clean water is limited.
Wild polio viruses ceased to circulate in most of the United States by 1970, at which time only 65 percent of children were receiving a complete course of live oral polio vaccine. (Pg 290)
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From 1923 to 1953, before the Salk killed-virus vaccine was introduced, the polio death rate in the United States and England had already declined on its own by 47 percent and 55 percent, respectively. Source: International Mortality Statistics (1981) by Michael Alderson.
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Complications
A person’s response to a poliovirus infection can be highly variable and is categorized on the severity of their symptoms.
Nearly 95% of all poliovirus cases are asymptomatic or inapparent and less then 1% will lead to flaccid (reduced muscle tone) paralysis. Many people with paralytic polio will recover completely and the majority will experience muscle function return in various degrees.
1-2% of infected individuals will suffer from nonparalytic aseptic meningitis (stiffness of the neck, back or legs). Typically these symptoms will last from 2 to 10 days followed by a complete recovery.
Death rates for paralytic polio cases (remember this is <1% of cases) are approximately 2-5% for children with higher numbers seen in adults (15-30%).
The Vaccines
I will only be discussing in detail the IPV (injectable polio) vaccines since the OPV (live, oral polio) vaccine is no longer employed in the US since 2000. This is due to the efforts to eliminate VAPP (vaccine-associated paralytic polio, aka polio caused by the oral vaccine).
It is believed that 90 percent of individuals who receive the polio vaccine will develop antibodies to all three polio virus types after two doses with 99% following the third dose. Protection is assumed and correlated with the presence of antibodies.
Because the injectable vaccine (IPV) produces less gastrointestinal immunity then the oral vaccine, persons who complete the schedule with the IPV are more readily infected with wild-type polio then OPV recipients.
Duration of immunity from IPV is not known, however it is assumed to provide “many years” of protection after the complete series is finished (according to the CDC).
There are three combination vaccines doctors use in the US that contain the inactivated polio vaccine. The acceptable schedule approved by the ACIP for IPV consists of four doses (2 months, 4months, 6-18 months, and 4 years). The first three doses are routinely administered with other vaccines.
IPOL (Sanofi Pasteur)
IPOL is the only singleton polio vaccine and can be used in children 6 weeks old to adulthood.
According to the package insert, interruption of the recommended schedule with a delay between doses does not interfere with the final immunity. There is no need to start the series over again, regardless of the time elapsed between doses.
Pediarix (GlaxoSmithKline)
Pediatrix contains DtaP, hepatitis B and IPV – this vaccine can be used for the first 3 doses (2month, 4month, 6-18 months) of the DtaP series among ages 6weeks through 6 years.
Each 0.5-mL dose contains aluminum as an adjuvant (not more than 850 mcg aluminum), ≤100 mcg of residual formaldehyde and ≤100 mcg of polysorbate 80 (Tween 80).
The safety study performed in the US for licensure consisted of a control group (335 infants) receiving the Hib conjugate vaccine (Wyeth; no longer licensed in the US) and 7-valent pneumococcal conjugate vaccine (Wyeth). No saline solution group was employed.
The rate of fever (greater then 100.4 degrees F) is significantly higher in the group that received Pediarix compared to separately administered vaccines. Other statistically significant adverse events include: pain, redness, swelling, drowsiness, irritability, and loss of appetite.
It is noted in the package insert that some cases of SIDS can be expected to follow receipt of pertussis-containing vaccines.
Kinrix (GlaxoSmithKline)
Kinrix contains DtaP and IPV – this vaccine is approved for children 4 yrs-6yrs which means that Kinrix is normally employed for the 5th dose of DtaP and fourth dose of IPV.
Each 0.5-mL dose contains aluminum as an adjuvant (not more than 60 mcg aluminum), ≤100 mcg of residual formaldehyde and ≤100 mcg of polysorbate 80 (Tween 80).
Adverse side effects reviewed in the clinical trials that were statistically significant were pain (statistically higher compared to IPOL), redness, swelling, drowsiness, loss of appetite and fever (statistically higher compared to IPOL). The placebo group used in clinical trials to assess safety was IPOL+Infanrix. No saline solution group was employed.
Pentacel (Sanofi Pasteur)
Pentacel contains DtaP, Hib and IPV – when this vaccine is used to provide the recommended 4 doses, an additional booster dose is suggested at age 4-6 years. This will result in a 5-dose IPV series.
Each 0.5 mL dose includes aluminum as an adjuvant (330 mcg aluminum), polysorbate 80 (approximately 10 ppm by calculation), and ≤5 mcg residual formaldehyde.
The placebo group used to assess safety was the Daptacel vaccine, Daptacel+IPOL+ActHIB and Daptacel+ActHIB. No saline solution group was employed.
Significant adverse events reviewed in the clinical trials were fever, decreased activity (lethargy), inconsolable crying and irritability.
Pentacel is the most reactive vaccine for polio. Serious adverse events 30 days after vaccination were reported more often then any other control groups in the safety assessment. Of these adverse reaction, events reported consist of: bronchiolitis, dehydration, pneumonia, asthma and gastroenteritis.
OPV
All of the vaccines listed above are inactivated poliovirus vaccines which do not contain live viruses, so they cannot cause VAPP (vaccine associated polio paralysis). However, the oral polio vaccine (OPV) is still administered to children and adults in countries around the world.
It is said that the advantages of using OPV in developing nations seem to outweigh the risk of vaccine-induced polio (the OPV is more cost effective). However, mutant strains (virus revertants) of vaccine-virus polio have been reported and have infected people in Hispaniola, the Philippines and Madagascar.
SV40 Contamination
SV40 (simian vacuolating virus 40) is a DNA-virus found in monkeys that has the potential to cause tumors. It was discovered in 1960, that same year SV40 was found to contaminate IPV vaccines.
That next year, in 1961, the virus was found to cause tumors in rodents. Following that discovery, the US government required new stocks of polio vaccine free of SV40.
The contaminated vaccines were not recalled and continued to be used for 3 more years following the discovery. Over 98 million US citizens received at least one dose of polio vaccine contaminated with SV40.
The current inactivatd polio vaccines (IPV) are free of contamination that we are curretly able to test for.
Whenever you make a health care decision for yourself or your child, especially one that involves a pharmaceutical product such as a vaccine, you should consider obtaining information from many different sources as well as consulting your health care professional.
Becoming an informed health care consumer is important and will empower you to ask doctors important questions and ultimately help you to take control of your health choices.
If your doctor is not supportive of your informed health choices, consider consulting another doctor who will work with you as a partner helping you make important health care decisions for yourself or your child(ren).
Information presented on this post can be reviewed in depth from the following sources:
