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Safety > Issues of Interest > AIDS
Oral Polio Vaccine and
HIV / AIDS:
Questions and Answers
Human
Immunodeficiency Virus (HIV)
Acquired Immunodeficiency Syndrome (AIDS)
Background
In the early 1990s an article in Rolling Stone
magazine introduced the idea that an experimental
oral polio vaccine used in the late 1950s may
have caused the AIDS epidemic. In 1999 the
idea was presented again in Mr. Edward Hooper’s
book ‘The River’. In response to
these publications, research has been done
to test the validity of the oral polio vaccine/HIV
theory. Evidence about the genetic origin and
characteristics of HIV, the production of the
experimental oral polio vaccine, and the lack
of HIV/AIDS epidemics in some areas where the
experimental oral polio vaccine was given all
suggest that the experimental vaccine was not
the source of HIV and AIDS in people. Furthermore,
some of the remaining experimental vaccine
was recently tested and did not contain HIV
or HIV-like viruses. In conclusion, scientists
believe that the experimental oral polio vaccine
did not cause the HIV/AIDS epidemic.
Current
oral polio vaccines are not related to the
experimental vaccine used in Africa in the
1950s. Modern vaccines are always tested before
use and DO NOT contain HIV. Immunization is
one of the most effective health interventions
in the world. Parents should continue to have
their children vaccinated against polio and
other childhood diseases. There is no reason
to fear that children will be infected by HIV
through polio vaccination.
- What
is polio?
Poliomyelitis,
or Polio, is caused by a virus that lives
in the throat and intestinal tract. It is
spread through contact with the bowel movements
of an infected person (for example, by changing
diapers). Polio can cause cold-like symptoms,
pain and stiffness in the neck, back, and
legs, and, in the worst cases, paralysis
or death. Polio was one of the most dreaded
childhood diseases of the first half of the
20th Century in the United States. Polio
vaccine became available in 1955 and because
of vaccination the disease has disappeared
from the U.S., and efforts are underway to
eliminate polio from the rest of the world
as well. It would only take one case of polio
from another country to bring the disease
back if we were not protected through vaccination.
- What
is polio vaccine and is it safe?
Polio vaccine protects people against polio.
There are two types of polio vaccine: Inactivated
polio vaccine, called IPV, which is given
as a shot (the polio virus used in this vaccine
is killed); and live oral polio vaccine,
called OPV, which is a liquid that is swallowed
(the virus used in this vaccine is attenuated
or weakened). Currently in the U.S. we use
only IPV, but in parts of the world where
polio still exists people get vaccinated
with OPV. Both OPV and IPV protect against
polio, but OPV is better at keeping the disease
from spreading to other people. However,
in rare cases (about 1 in 2.4 million), OPV
actually causes polio. Since the risk of
getting polio in the U.S. is now rare, experts
believe that the benefits of OPV no longer
outweigh the slight risks. IPV does not cause
polio or any other serious problems. Some
people who get IPV get a sore spot where
the shot was given, but most don’t
have any problems at all with it.
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- How
is polio vaccine made?
IPV is made with dead polio virus. The virus
is grown in a lab on a type of monkey kidney
cell culture and then killed with formaldehyde
or other chemical(s) harmful to the virus.
The chemicals are removed before the dead
virus is added to the vaccine. OPV is made
with live polio virus that has been weakened
so that it does not have enough strength
left to cause disease. Polio virus that is
used to make OPV is also grown in a lab on
monkey kidney cell culture and then weakened
using chemicals, freezing and dilution before
being given to people as a vaccine..
- When
were polio vaccines first developed and tested?
The first polio vaccines were developed and
tested in the 1950s. Jonas Salk introduced
the first widely used vaccine in 1954, which
was given to people as a shot (IPV). A short
time later Salk’s shot was replaced
by an oral polio vaccine (OPV) developed
by Albert Sabin. This vaccine was placed
on a sugarcube and eaten. In 1957 another
scientist, Dr. Hilary Koprowski, began vaccinating
people with an experimental oral polio vaccine
(OPV) that was dropped into the recipient’s
mouth and swallowed.
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- Were
animals used in developing and testing polio
vaccines?
Testing on animals, especially animals that
are closely related to humans such as monkeys
and chimpanzees, gave researchers a good
idea about the safety and efficacy of their
vaccine before giving the vaccine to people.
Early polio vaccine tests were done with
rabbits, mice, guinea pigs, chimpanzees and
monkeys. Also, animal organs were used to
grow the polio virus that was killed or weakened
to make the vaccines. Monkeys were the most
common animal used to grow the polio virus
for early vaccines.
- Is
it true that HIV originally came from monkeys
and apes?
There are two types of HIV (human immunodeficiency
virus) that can cause AIDS, HIV-1 and HIV-2.
HIV-1 causes most cases of AIDS in the U.S.,
only a few cases of HIV-2 have been found
in the U.S. HIV-2 is mostly an infection
of persons from West Africa. Scientists think
that HIV-1 evolved from an immunodeficiency
virus found in chimpanzees (simian immunodeficiency
virus, or SIVcpz). Viruses that infect one
species of animal, such as chimpanzees, generally
don’t infect other species of animals,
such as humans. Therefore, scientists do
not know exactly how or why this particular
virus ‘jumped’ from chimpanzees
to people—also known as ‘cross-species
transmission’. Scientists do believe,
however, that SIVcpz evolved into HIV-1 many
decades ago. DNA and genetic test results
of HIV-1 indicate that it may have crossed
into humans in the 1930s (Korber et al. 2000,
Hahn et al. 2000). HIV-2 is believed to have
come from a cross-species transmission of
an SIV from a sooty mangabey monkey (SIVsm)
(Hahn et al. 2000).
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- What
theory on polio vaccine and the origin of
AIDS is described by Mr Edward Hooper in
The River?
Mr. Hooper describes a theory that HIV was
introduced by an experimental oral polio
vaccine used in Central Africa in the 1950s.
The vaccine (from the CHAT strain) was produced
by Dr. Hilary Koprowski and his colleagues
at the Wistar Institute.
- Is
Dr. Koprowski’s vaccine related to
the polio vaccines now being used worldwide?
No, the current oral polio vaccine was developed
by Dr. Albert Sabin, uses Sabin strains and
bears no relationship to the experimental
vaccine. Furthermore, modern polio vaccines
are demonstrated to be free of HIV.
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- Is
there any evidence that supports the theory
that HIV was introduced by an experimental
oral polio vaccine?
The theory relies almost exclusively on the
coincidental appearance of the earliest documented
cases of AIDS near some of the sites where
the vaccine was tested in Central Africa.
- Where
was the vaccine used and how many people
were vaccinated?
The vaccine of Dr Koprowski was given to
7.2 million people in Poland, 1.5 million
in Croatia, 215,000 in Burundi, 76,000 in
the former Belgian Congo (now the Democratic
Republic of the Congo) and 34,000 in Switzerland.
The vaccine tested in Poland and Kinshasa
(DR Congo) was from the same vaccine lot.
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- Did
early cases of HIV appear wherever the Koprowski
vaccine was tested?
No. The vaccine was tested in several places
in Europe and Africa, including Poland, Switzerland,
Croatia, Burundi and Kinshasa (DR Congo).
Early cases of AIDS were seen only in Central
Africa. If the vaccine had been contaminated
with HIV or a similar virus, it is likely
that at least some of the people who were
vaccinated in the European countries would
have contracted the virus as well.
- What
is the explanation for the fact that some
of the areas where the Koprowski oral polio
vaccine was given were close to the areas
where the first AIDS outbreaks were seen?
The areas where Koprowski’s vaccine
was used and where the first AIDS outbreaks
occurred are also areas where chimpanzees
that carry SIV live. So it makes sense that
those areas were the same areas where SIV
‘jumped’ from chimpanzees to
people, and HIV-1 and AIDS were first seen.
Though some people believe that Dr. Koprowski
did use chimpanzee organs to grow the virus
for the vaccine, evidence indicates that
chimpanzees were only used to test the vaccine,
not to produce it.
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- If
so many people in various places received
the Koprowski vaccine, how does Mr Hooper
explain that there were not a large number
of AIDS cases appearing simultaneously?
Mr. Hooper suggests that the suspect vaccine
only had low level contamination or that
only certain lots of vaccine were contaminated.
- Is
there any documentation that early AIDS cases
actually received the vaccine?
No, there are no records to show that the
AIDS cases did in fact receive the vaccine.
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- How
does Mr. Hooper suggest the vaccine could
have become contaminated?
Mr. Hooper suggests that all of the following
events might have occurred: (1) chimpanzee
tissues contaminated with an HIV-like virus
were used in the production of the experimental
vaccine lots, (2) an HIV-like virus grew
during vaccine production and (3) HIV could
be transmitted during oral vaccination.
- Was
chimpanzee tissue used to produce the vaccine?
No, the vaccine was produced in cells from
Asian monkeys, of India or the Philippines,
which do not carry HIV-like viruses. Mr.
Hooper’s book relies on the assumption
that some vaccine was produced using chimpanzee
tissues outside of standard protocols.
- Will
HIV or HIV-like viruses grow in cell cultures
like those used to produce the vaccine?
No, HIV and related viruses do not grow in
cultures of kidney cells like those used
to produce the vaccine.
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- If
an oral polio vaccine were contaminated with
an HIV-like virus, would that result in infection
of vaccine recipients?
It is very difficult to transmit HIV by the
oral route. It is highly unlikely that HIV
infection would result from a vaccine given
by mouth.
- If
chimpanzees are the source of HIV, are there
other ways that humans could have become
infected from them?
There is evidence that chimpanzees may be
the original source of HIV. It has been clear
since the earliest years of the AIDS epidemic
that HIV is most efficiently spread by blood
and sexual fluids. Chimpanzees are hunted
for food in Central Africa. Exposure to chimpanzee
blood during hunting and preparing the carcass
for food could result in infection through
skin cuts or other lesions. Hunters could
have spread HIV-like virus to others through
sexual contact. It has been suggested that
urbanization, the breakdown of traditional
family life, new attitudes about sexuality
and improved transportation all facilitated
the spread of AIDS.
- Was
the experimental vaccine tested for HIV?
The vaccine was not tested for HIV in the
1950s because no one knew about the virus
then. Tests for HIV and related viruses did
not become available until the 1980s. However,
some of Dr. Koprowski’s vaccine that
had been stored in a lab was recently tested
and did not contain any HIV or HIV-like viruses.
Furthermore, the vaccine tests did not show
any evidence of chimpanzee cells, which suggests
that chimpanzee organs were not used to grow
the virus for the vaccine and the vaccine,
therefore, was not contaminated with SIV,
the HIV-like virus. (Cohen 2000, Cohen 2001,
Horton 2000, Rizzo et al. 2001, Weiss 2001).
- Can
testing of the vials of material used to
make the Koprowski vaccine prove that the
theory is not correct?
No. Mr Hooper and others have stated that
a negative test could be due to the vials
coming from the wrong lots, having been improperly
stored or the test being insufficiently sensitive
to detect the postulated extremely low level
of contamination.
- Have
polio vaccines ever been contaminated with
other viruses?
Yes. Some of the first Salk polio vaccines
and Sabin polio vaccines were contaminated
with SV-40, a virus found in some species
of monkey. SV-40 is not related to HIV. Studies
have shown no increased rates of disease
among persons who received that vaccine.
Modern vaccines do not contain SV-40. The
Sabin vaccine seed strains, which are used
to make modern OPV, have been repeatedly
tested using very sensitive assays and shown
to be free of any virus contamination.
- Is
it possible to get HIV from vaccines that
are used today?
No--All vaccines used today have to go through
testing and evaluation before and after they
are licensed for use. This begins with extensive
testing in labs and animals, followed by
three phases of testing on groups of human
volunteers. In addition, tissues and cells
used to grow and produce any biological item,
such as vaccines, are required to be tested
and cleared of any viruses, including HIV
(FDA 1993). If a vaccine passes all of these
rigorous scientific tests it may be approved
by the Food and Drug Administration (FDA)
and licensed for use. The FDA and CDC continue
to monitor a vaccine, even after it is tested
and licensed, to make sure that it continues
to be safe (for more information, see www.fda.gov/cber/vaccines.htm).
The
Vaccine Adverse Event Reporting System,
or VAERS, was designed to give health care
workers and others a place to report negative
reactions following vaccination. VAERS
helps the FDA and CDC to continuously monitor
vaccine safety. To request
a VAERS form or to get more information
about VAERS please go to http://www.vaers.org/
or call 1-800-822-7967.
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References
Cohen
J. Disputed AIDS theory dies its final death.
Science 2001;292:615.
Cohen J. Vaccine
theory of AIDS origins disputed at Royal Society.
Science 2000;289:1850-1851.
FDA. Points
to consider in the characterization of cell
lines used to produce biologicals. 1993 http://www.fda.gov/cber/gdlns/ptccell.htm#i.
Hahn B, Shaw
G, De Cock K, Sharp P. AIDS as a zoonosis:
scientific and public health implications.
Science 2000;287:607-614.
Horton R. New
data challenge OPV theory of AIDS origin. Lancet
2000;356:1005.
Korber B, Muldoon
M, Theiler J, Gao F, Gupta R, Lapedes A, Hahn
BH, Wolinsky S, Bhattacharya T. Timing the
ancestor of the HIV-1 pandemic strains.
Science 2000;288:1789-1796.
Rizzo P, Matker
C, Powers A, Setlak P, Heeney JL, Ratner H,
Carbone M. No evidence of HIV and SIV sequences
in two separate lots of polio vaccines used
in the first U.S. polio vaccine campaign. Virology
2001;287:13-17.
Weiss R. Polio
vaccines exonerated. Nature 2001;410:1035-1036.
See
also: FACT
SHEET on Polio Vaccine and HIV/AIDS |
