Questions and Answers on Bovine Spongiform Encephalopathy
Questions and Answers on Bovine Spongiform
Encephalopathy:
- What is BSE?
- What causes BSE?
- Where is the BSE agent
found in infected cattle?
- Which countries have
reported BSE?
- How was BSE spread?
- What has the British
government done in response to the BSE epidemic?
- Does BSE occur in the US?
- What measures has the US
government taken to ensure that BSE does not occur in the US, and
that people are not exposed to the BSE agent in foods?
- How is the BSE agent
detected?
- Does BSE or a similar
disease occur in humans?
Questions and Answers on Variant CJD (vCJD):
- What is the new variant
form of CJD that the experts in the United Kingdom believe might be
related to the BSE outbreak in cattle?
- Exactly how does this
newly recognized variant of CJD differ from classical CJD?
- How did people get this
new variant of CJD?
- What is the evidence
directly linking this newly recognized variant of CJD to BSE
exposure?
- How many cases of variant
CJD have occurred?
- Could anyone in Europe
diagnosed with the newly recognized variant of CJD (vCJD) have
acquired this from vaccines?
Questions and Answers on Bovine Derived Materials
Used in Vaccine Manufacturing:
- Why are animal products
used in the manufacture of vaccines?
- Which bovine derived
materials are used in vaccine manufacture?
- Do all bovine materials
have the same risk of transmitting the BSE agent?
- What measures have the
FDA taken to ensure that people are not exposed to the BSE agent in
vaccines?
Questions and Answers Related to FDA Guidance on
Sourcing of Bovine Materials:
- How did the FDA discover
that some manufacturers are not universally following letters,
Points to Consider (PTC) and guidance documents?
- What is FDA doing now to
assure that companies follow guidance, letters, and PTC documents?
Questions and Answers Related to Vaccines and vCJD:
- Why did the FDA ask the
Transmissible Spongiform Encephalopathy Advisory Committee (TSEAC)
and the Vaccines and Related Biological Products Advisory Committee
(VRBPAC) meet on July 27th, 2000?
- What is the chance/risk
that a vaccine on the market in the US contains the BSE agent?
- What is the risk of
getting vCJD if a vaccine contained the BSE agent?
- How did FDA derive its
risk estimates and decide the risk of vCJD from vaccines was remote
and theoretical?
- Why is FDA leaving
vaccines on the market that did not follow its own recommendations
regarding sourcing of bovine derived materials?
- If vaccines are safe, why
did the UK recall the polio vaccine?
- What is the recent concern
in the Republic of Ireland about polio vaccine and vCJD?
- Have there been vaccines
produced using cow materials from countries where there is a
significant risk of BSE?
- Is there a possibility
that some vaccines might be contaminated with the BSE agent?
- My child was just
immunized. Should I be worried?
- Why are you continuing to
vaccinate children with a vaccine that may be contaminated with BSE
causing materials?
- What is being done to
ensure the United States’ vaccine supply is safe?
- When will vaccine
manufacturers finish replacing cow-derived materials in vaccines
with materials obtained from countries free of BSE?
- Shouldn’t all potentially
contaminated vaccines be destroyed?
What is BSE?
BSE (bovine spongiform encephalopathy) is a progressive neurological
disorder of cattle; its symptoms are similar to a disease of sheep,
called scrapie. "BSE has been called "mad cow disease."
BSE and scrapie both result from infection with a very unusual infectious
agent. As of July 2000, more than 176,000 cases of BSE were confirmed in
Great Britain in more than 34,000 herds of cattle. The epidemic peaked in
January 1993 at almost 1,000 new cases per week. The outbreak may have
resulted from the feeding of scrapie-containing sheep meat-and-bone meal
to cattle. There is strong evidence and general agreement that the
outbreak was amplified by feeding meat-and-bone meal prepared from cattle
to young calves.
What causes BSE?
The nature of the infectious agent that causes BSE and scrapie is
unknown. Currently, the most accepted theory is that the agent is a
modified form of a normal cell protein known as a prion. A prion is not a
bacterium, parasite, or virus, and thus treatments usually used for
treating or preventing bacterial infections (e.g. antibiotics) or viral
infections are not effective against prions.
Where is the BSE agent found in cattle?
In cattle naturally infected with BSE, the BSE agent has been found in
brain tissue, in the spinal cord, and in the retina of the eye.
Additional experimental studies suggest that the BSE agent may also be
present in the small intestine, bone marrow, and dorsal root ganglia.
Which countries have reported BSE?
The vast majority of cases of BSE (more than 99% as of 1999) have been
reported from the United Kingdom during an epidemic. However, endemic
cases have also been reported in other European countries including: the
Republic of Ireland, Switzerland, France, Liechtenstein, Luxembourg,
Netherlands, Portugal and Denmark. The numbers of reported cases by
country are available on the web site of the Office International des
Epizooties (www.oie.int/). These
numbers should be interpreted with caution, however, because the
intensity and methods of surveillance probably vary over time and by
country.
How was BSE spread?
It is thought that BSE was spread via meat-and-bone meal fed to
cattle. The practice of using this material as a source of protein in
cattle feed has been common for several decades. In the late 1970s there
was a change in the production (rendering) process used to make this meat
and bone meal. One hypothesis is that this change permitted the
infectious agent of scrapie (a transmissible spongiform encephalopathy,
or TSE, of sheep) to survive the rendering process, and get transmitted
to other animals, such as cows, that are fed meat-and-bone meal
nutritional supplements.
What has the British government done in response to the BSE
epidemic?
In response to the BSE epidemic, the British Government instituted a
series of measures to minimize the risk of disease transmission among
both animals and humans. These included a ban on feeding ruminant protein
(ruminants are animals, such as cows, sheep and goats) to ruminants
(1988), removal of some "high risk" materials (such as brain,
spinal cord and intestines) from cattle at slaughter (1989 and 1995), and
a ban on cattle over 30 months of age from being used for food (1996).
Following institution of these measures, Great Britain has seen a
decrease in the number of cattle with BSE from a peak incidence of 36,680
confirmed cases in 1992 to 2,254 confirmed in 1999 (information on the
BSE epidemic in Great Britain is available at: www.maff.gov.uk).
Does BSE occur in the US?
According to the Animal and Plant Health Inspection Services (APHIS)
of the United States Department of Agriculture, BSE has not been detected
in the United States, despite active surveillance efforts for several
years. As of May 31, 2000, 10,670 cow brains have been examined by US
inspectors, and no evidence of BSE was seen. Further, to prevent BSE from
entering the United States, severe restrictions have been placed on the
importation of live ruminants and certain ruminant products from
countries where BSE was known to exist. Recently, these restrictions were
extended to include importation of ruminants and certain ruminant
products from all European countries.
What measures has the US government taken to ensure that BSE
does not occur in the US, and that people are not exposed to the BSE
agent in foods?
The USDA is responsible for the health of US livestock. To prevent BSE
from entering the country, the USDA Animal and Plant Health Inspection
Service (APHIS) has, since 1989, prohibited the importation of live
ruminants from countries where BSE is known to exist in native cattle. On
December 12, 1997, APHIS stopped the importation of live ruminants and
most ruminant products, including meat, meat-and-bone meal, offals,
glands, etc. from all of Europe. FDA is responsible for food safety in
the US. In August 1997, FDA prohibited the use of most mammalian protein
in the manufacture of animal feeds given to ruminants. In addition, the
final regulation also requires quality control procedures to make sure
that ruminant feed does not contain the prohibited mammalian tissues. The
USDA leads an interagency surveillance program for evidence of BSE in the
US. No cases of BSE have been confirmed in the US despite 10 years of
active surveillance.
How is the BSE agent detected?
The presence of the BSE agent in tissues is generally determined by
injecting animals, usually mice, with material believed to be infected
with BSE, then observing the mice to see if they die and have
characteristic brain tissue changes. Mouse inoculation studies take a
long time (up to 700 days) to detect the agent, and a negative result
(that is, lack of brain tissue changes in the injected mice) may only
mean that there was too little of the infectious agent to cause symptoms,
not that the material was really free of the infectious agent altogether.
It is also possible to detect the presence of the abnormal prion protein
in tissues (such as brain) using special staining procedures although
these methods do not allow an accurate assessment of infectivity of the
infected material.
Does BSE or a similar disease occur in humans?
BSE belongs to a group of progressive degenerative neurological
diseases known as transmissible spongiform encephalopathies (TSEs). TSE
diseases are always fatal. The TSE diseases include scrapie, which
affects sheep and goats; transmissible mink encephalopathy; feline (cat)
spongiform encephalopathy; and chronic wasting disease of deer and elk.
There are six TSE diseases that affect people: kuru, classical
Creutzfeldt- Jakob disease (CJD) and variant Creutzfeldt-Jakob disease
(vCJD), Gerstmann-Sträussler-Scheinker syndrome, fatal familial insomnia,
and sporadic fatal insomnia. The human diseases are very rare; for
example, classical CJD has been well studied and occurs sporadically
worldwide at a rate of about one case per one million people.
Questions and Answers on Variant CJD (vCJD)
What is the new variant form of CJD that the experts in the
United Kingdom believe might be related to the BSE outbreak in cattle?
In contrast to the classic form of CJD, the new variant or variant
form (vCJD) in the United Kingdom and France affects younger persons
(average age at onset: 28 years), and has different clinical features
from CJD. People with vCJD begin with serious psychiatric problems or
problems with their senses (ears, eyes or smell). This first set of
symptoms is followed weeks or months later by poor muscle coordination,
problems with muscle spasms, and mental confusion; these patients also
have abnormal electroencephalograms (EEG). The illness lasts for at least
6 months, and on average people with vCJD die approximately 13 months
after their symptoms begin. When patients’ brains are examined by
autopsy, there are clear changes in brain tissue structure, including
many "spongiform," or open spongy-looking areas, abnormal spots
of prion protein called plaques, and other areas with much prion protein
accumulation.
Exactly how does this newly recognized variant of CJD differ
from classical CJD?
In 1996 the Spongiform Encephalopathy Advisory Committee (SEAC) of the
UK announced the identification of 10 cases of variant CJD (vCJD, Lancet,
1996, 347: 921-25). The following features describe how vCJD cases differ
from the sporadic or classical form of CJD:
- The affected individuals
were much younger than the classical CJD patient. Typically, CJD
patients are over 63 years old. The average patient with vCJD is 28
years old; patients ranged from 12-52 years old.
- The course of vCJD
averaged 13 months. Classical CJD cases average a 6 month duration.
- In the vCJD cases,
electroencephalographic (EEG) electrical activity in the brain was
not typical of classical CJD.
- Although changes in brain
tissue structure of patients with vCJD were recognizable as CJD, the
pattern was different from classical CJD, with large aggregates of
prion protein plaques often surrounded by vacuoles.
How did people get this new variant of CJD?
On March 20, 1996 a statement from the Spongiform Encephalopathy
Advisory Committee (SEAC) of the United Kingdom indicated concern that
before November 1989, when inclusion of certain cow and sheep by-products
in human food was banned, the BSE agent may have been transmitted to
people through contaminated food products. The SEAC said that food might
account for the 10- vCJD cases described in April, 1996 in the medical
literature (Lancet 1996; 347:921-5). The specific foods, if any, that may
be associated with the transmission of this agent from cattle to humans
are unknown. However, the SEAC has indicated that milk and milk products
are unlikely to pose any risk for human exposure to the BSE agent.
What is the evidence directly linking this newly recognized
variant of CJD to BSE exposure?
There is strong epidemiologic and laboratory evidence suggesting that
new variant CJD (vCJD) and BSE are caused by the same infectious agent.
For instance, there have been no confirmed cases of vCJD in other
geographic areas where there have been no BSE cases. In addition, the
time interval or "incubation period" between the most likely period
for the initial exposure of the population to potentially
BSE-contaminated food (1984-1986) and onset of initial vCJD cases
(1994-1996), about 10 years, is similar to the known time intervals
between exposure to the classical CJD agent and the development of CJD.
An experimental study reported in June 1996 showed that three cynomologus
macaque monkeys that were injected with brain tissue from cattle with BSE
later developed symptoms and changes in brain tissue that were strikingly
similar to vCJD (Nature 1996;381:743-4). Another study published in 1996
showed that prions obtained from 10 vCJD patients and BSE-infected
animals had molecular characteristics that were similar to each other but
that were distinct from prions obtained from patients with classical CJD
(Nature 1996;383:685-90). Furthermore, intermediate results of an ongoing
experimental study involving injection of a panel of mice with the agent
that causes BSE and vCJD suggest that these agents cause a similar
disease in mice (Nature 1997;389:498-501). A recent study using
transgenic mice (PNAS 1999; 96:15137-15242) supports the hypothesis that
the BSE agent from cattle causes vCJD.
How many cases of variant CJD have occurred?
Cases of variant CJD are very rare, and most have occurred in the
United Kingdom. The latest information (March 5, 2001) issued by the
Department of Health, United Kingdom (www.doh.gov.uk/cjd/)
indicates that there have been 85 confirmed cases of vCJD in the United
Kingdom. These cases have all been diagnosed since 1995. France has
reported two cases. The Republic of Ireland reported one case in 1999. No
cases have been recognized in other European countries, or in the United
States
Could anyone in Europe diagnosed with the newly recognized
variant of CJD (vCJD) have acquired this from vaccines?
In the UK the majority of cases of vCJD were born before 1980, and it
is very unlikely that they received vaccines contaminated with the BSE
agent (Vaccine 2000 19:409-410). Surveillance of vCJD in the UK has
identified three "risk factors," or characteristics common to
most if not all of the people who had vCJD: i) residence in the UK; ii) a
particular genetic susceptibility (met/met homozygosity at codon 129 of
the PrP gene); and iii) age. Epidemiological evidence to date suggests
that these cases of vCJD acquired the disease from eating beef products
containing the BSE agent after 1980. To date (March, 2001) there have
been 88 confirmed cases of vCJD. Of these, 85 have occurred in the UK. A
case of vCJD was reported in the Republic of Ireland in June 1999 in a
person who had been a UK resident from 1989-1995. Two cases of vCJD have
been diagnosed in France, one in 1996 and the other in 1999. Neither of
these people had lived or traveled in the UK. However, according to data
published by the UK (HM Customs and Excise), France was a leading
European importer of bovine products during the period 1980-1996. No
other cases of vCJD have been found in Europe.
Questions and Answers on Bovine Derived Materials Used in
Vaccine Manufacturing:
Why are animal products used in the manufacture of vaccines?
Vaccines contain either killed or weakened forms of disease-causing
bacteria or viruses, or components of these that stimulate a response by
the body’s immune system, which then protects against the development of
disease. In the late 19th century, microbiologists began to
grow bacteria in the laboratory. The early bacteriologists tried to mimic
as closely as possible the infected person’s tissues by using sugars,
salts, and various meat extracts to make "growth media." These
kinds of conditions were quite successful in growing bacteria and then
viruses in the lab, because these media supplied the many necessary
nutrients. Although synthetic media have been developed for growth of
many medically important microorganisms, some still require additional
nutrients which are easily provided by animal-derived products such as
serum and blood.
Which bovine derived materials are used in vaccine
manufacture?
Microorganisms for vaccine manufacture are grown under controlled
conditions in media which provide the nutrients necessary for growth. Cow
components are often used simply because cows are very large animals, and
thus much material is available. Animal-derived products used in vaccine
manufacture can include amino acids, glycerol, detergents, gelatin,
enzymes and blood. Cow milk is a source of amino acids, and sugars such
as galactose. Cow tallow derivatives used in vaccine manufacture include
glycerol. Gelatin and some amino acids come from cow bones. Cow skeletal
muscle is used to prepare certain complex media. Many difficult to grow
microorganisms require the addition of serum from blood to the growth
media.
Do all bovine materials have the same risk of transmitting the
BSE agent?
Scientists have found that different bovine tissues contain different
amounts of the BSE agent. It is generally believed that the highest
amounts of infectivity are found in the brain and spinal cords from
animals in the final stages of clinical disease. Some tissues such as
skeletal muscle and milk have never been shown to have any infectivity.
However, the slaughtering and butchering methods used to obtain tissues
and prepare materials can affect the amount of infectivity that may be
present. Also the production processes used to prepare bovine-derived
materials (such as heat sterilization and chemical treatment) may reduce
or remove infectivity.
What measures have the FDA taken to ensure that people are not
exposed to the BSE agent in vaccines?
It is believed that variant CJD was acquired from eating food products
containing the BSE agent. However, FDA wants to minimize any chance that
the BSE could be introduced into biologic products during manufacture.
The Center for Biologics Evaluation and Research (CBER) is responsible
for regulation of biologic products, including vaccines. In a 1991 letter
to manufacturers CBER expressed concern about bovine sourced material. In
December 1993 and May 1996 FDA issued letters advising that bovine
derived materials from animals born in or residing in countries where BSE
had occurred should not be used to manufacture FDA-regulated products
intended for administration to humans. A 1993 Points to Consider document
("Points to Consider in the Characterization of Cell Lines Used for
the Production of Biologics") stressed the importance of control of
sourcing of bovine materials. On April 19, 2000, CBER issued a letter
reminding manufacturers that the USDA list of BSE-countries had been
expanded to include not only those countries where BSE was known to exist
but also those where BSE may exist (FR, January 6, 1998). CBER strongly
recommended "that manufacturers take whatever steps are necessary to
assure that materials derived from all species of ruminant animals born,
raised or slaughtered in countries where BSE is known to exist, or
countries where the USDA has been unable to assure FDA that BSE does not
exist, are not used in the manufacture of FDA-regulated products intended
for administration to humans."
Questions and Answers Related to FDA Guidance on Sourcing of
Bovine Materials:
How did the FDA discover that some manufacturers are not
universally following letters, Points to Consider (PTC) and guidance documents?
During review of new license applications manufacturers are asked to
provide detailed descriptions of the manufacturing process and
documentation of source country for all materials of animal origin.
During review of a recent license application it was determined that some
of the material used during manufacture had been obtained from countries
which are on the USDA list of countries which either have or may have
BSE. This finding prompted an inquiry of all licensed vaccines.
What is FDA doing now to assure that companies follow
guidance, letters, and PTC documents?
The Center for Biologics Evaluation and Research (CBER) has asked
licensed vaccine manufacturers to evaluate all bovine sourced material
used at any stage of manufacture. Manufacturers have been requested to
identify all material of animal origin. For materials of bovine origin
CBER has asked manufacturers to identify the source country from which
the animals originated, the date the material was obtained and the date
the material was used in manufacture of vaccine lots.
When it is determined that any bovine-derived component used to make
the working seeds or during routine production was obtained from a
country on the current USDA list of countries which either have or may
have BSE or from an unknown country, the manufacturer has been asked to
change the source of such material. CBER inspects vaccine manufacturers
on a routine basis to determine whether sourcing and documentation are
consistent with current recommendations contained in letters and guidance
documents.
Questions and Answers Related to Vaccines and vCJD:
Why did the FDA ask the Transmissible Spongiform
Encephalopathy Advisory Committee (TSEAC)and the Vaccines and Related
Biological Products Advisory Committee(VRBPAC) meet on July 27th,
2000?
The Center for Biologics Evaluation and Research (CBER), FDA regulates
biological products including vaccines. For several years CBER has
recommended that bovine derived components from countries which have or
may have BSE (bovine spongiform encephalopathy, the so called "mad
cow disease") not be used for the manufacture of US-licensed
biological products including vaccines. The consumption of food
contaminated with the BSE agent has been linked to a fatal disease in
people called new variant or variant CJD (vCJD). There is no evidence
that any case of vCJD has resulted from use of a vaccine, and there is no
evidence that any vaccines harbor the BSE agent. CBER had recently
determined that some vaccines were manufactured using bovine components
from countries which the USDA has determined have or may have BSE. CBER
believed that the chance of getting vCJD through vaccines is remote and
theoretical. However, CBER has responsiblility to ensure that vaccines
used in the US are safe and asked for this special joint meeting to ask
vaccine and TSE experts to formally discuss the risk of transmitting vCJD
from vaccines.
What is the chance/risk that a vaccine on the market in the US
contains the BSE agent?
Studies of the BSE agent have shown that infectivity depends on nature
of material used, how much is used and the route of administration. Other
factors, such as the country of origin of the cattle used to supply the
manufacturing material, also have to be factored into any risk estimate.
Both the European Community and the US Pharmaceutical industry have
presented risk assessment calculations which attempt to account for all
these factors. In 1999, the Council on Scientific Affairs (CSA) of the
American Medical Association considered the risk of BSE to public health
and determined that the current risk of transmission of BSE in the US is
minimal, concluding that adequate guidelines exist to prevent high risk
bovine materials from contaminating products intended for human use. The
report from the CSA did not address the possibility that regulated
industry might not follow all of the recommendations made by the FDA.
However, both FDA and the joint advisory committees (TSEAC and VRBPAC)
have considered the risks posed by bovine material in vaccines and
concluded that any risk is remote and theoretical See Section I, Section II and Section VI and MMWR Recommendations and Reports.
What is the risk of getting vCJD if a vaccine contained the
BSE agent?
There is no evidence to date that vaccines have contributed to the
cases of vCJD seen in Europe. Nor is there evidence that any vaccines
harbor the BSE agent. Vaccines are given a very limited number of times
via the intramuscular, subcutaneous or oral route. Even in experimental
studies, these routes of administration are less effective at spreading
the agent than the intracerebral route usually used to assess infectivity
in animal studies. The amount of infectivity present and the efficiency
with which the BSE agent passes from cow material to humans will also
affect the likelihood of infection.
How did FDA derive its risk estimates and decide the risk of
vCJD from vaccines was remote and theoretical?
Scientists, regulatory authorities in Europe and the pharmaceutical
industry of the US have considered the risks of BSE in pharmaceutical products.
In estimating these risks it is necessary to consider the country of
origin of any bovine material, the type of bovine tissue used, the steps
used to process the bovine tissue, the amount of bovine derived material
used and the stage of vaccine manufacture at which the bovine material is
used. Using previously published methods for calculating theoretical risk
of cases of vCJD from pharmaceutial products, FDA has calculated a
conservative estimation of the risk of a vaccine causing a case of vCJD. These
estimates were presented in public session at the joint advisory
committee on July 27th 2000. FDA believes these estimations
are a realistic worst case scenario and that the real risk any US
licensed vaccine could cause vCJD is even lower than the estimates
presented. See Section VI
and Section II.
Why is FDA leaving vaccines on the market that did not follow
FDA recommendations regarding sourcing of bovine derived materials?
One of FDA's main concerns is the safety of vaccines and other drugs
given to consumers. In its efforts to monitor the safety of products FDA
continually reviews the potential risk of products in relation to new
entities, including the BSE agent. The FDA has looked at the benefit of
vaccines and the risk of contamination of vaccines with the BSE agent.
The Public Health Service, FDA, and FDA’s advisory committees on
Transmissible Spongiform Encephalopathy (TSEAC) and Vaccines and Related
Biological Products (VRBPAC) believe the risk that anyone will get vCJD
from a vaccine to be remote and theoretical. Vaccines have a proven benefit
in reducing the incidence of serious, oftern life-threatening diseases.
The absence of high levels of of routine vaccination leads to an
increased incidence of vaccine preventable diseases. Therefore, removal
of licensed vaccines from the market for a remote, theoretical risk can
have serious medical and public health consequences. In considering the
balance of risks and benefits, the use of all vaccines, even those which
were manufactured with bovine derived materials from unapproved sources
should continue.
If vaccines are safe why did the UK recall their polio
vaccine?
The UK recalled the Evans/Medeva Oral Polio Vaccine in October, 2000.
This vaccine has never been licensed for use in the US. The Medicines
Control Agency (MCA) had requested and received assurances from drug
companies that they were implementing guidance not to use UK-sourced
bovine materials in the manufacture of injectable medicinal products. The
recall was prompted by evidence that the Evans/Medeva vaccine was
manufactured using fetal calf serum from the UK at a time when there was
a risk of BSE in that country. This is in contravention of European Union
guidelines. According to a statement from the Chief Medical Officer at
the UK Dept. of Health (10.20.00) the company had assured the MCA of the
UK that UK-sourced bovine materials were not used in the manufacture of
the vaccine. However, these assurances were inaccurate, thus the vaccine
was withdrawn. (www.doh.gov.uk/cmo/cmo00_12.htm)
What is the recent concern in the Republic of Ireland about
polio vaccine and vCJD?
In December, 2000 the Irish Government issued a statement indicating
that an oral polio vaccine distributed in 1998 and 1999 in Ireland had
been manufactured using human serum albumin from a pool of donors, one of
whom had since been diagnosed with vCJD. Evans/Medeva manufactured this
oral polio vaccine. This vaccine is not licensed for use in the US.
Have there been vaccines produced using cow materials from
countries where there is a significant risk of BSE?
During review of a new license application, FDA learned that one
manufacturer had used bovine-derived material from a country in which the
USDA had determined that BSE might exist. CBER requested all vaccine manufacturers
review the source of any bovine derived material used in the manufacture
of their vaccines. Additional vaccines manufactured using bovine derived
products from European countries were identified. These vaccines are
identified in the “Recommendations for the Use of Vaccines Manufactured
with Bovine Derived Materials” section of this web site. (See Section I)
Is there a possibility that some vaccines might be
contaminated with the BSE agent? (See above “What is the
chance/risk that a vaccine on the market in the US contains the BSE
agent”)
My child was just immunized. Should I be worried?
No. FDA and other Public Health Service agencies believe
that the risk of contamination of any US licensed vaccine with the BSE
agent is remote and theoretical. FDA asked a special joint meeting of the
Transmissible Spongiform Encephalopathy and the Vaccines and Related
Biological Products Advisory Committees to review the available vaccine
risk and benefit information. This joint committee concluded that the
substantial risk of disease due to not vaccinating children far outweighs
the theoretical risk posed by vaccines that have a remote chance of
containing the BSE agent (see PHS statement in MMWR and
“Recommendations for the Use of Vaccines Manufactured with Bovine Derived
Materials” section of this web site for details)
Why are you continuing to vaccinate children with a vaccine
that may be contaminated with BSE causing materials? Also
see above “Why is FDA leaving vaccines on the market that did not follow
its own recommendations regarding sourcing of bovine derived
materials."
FDA and other Public Health Service agencies believe that the risk of
contamination of any US licensed vaccine with the BSE agent is remote and
theoretical. FDA asked a special joint meeting of the Transmissible
Spongiform Encephalopathy and the Vaccines and related Biological
products Advisory Committees to review the available vaccine risk and
benefit information. This joint committee concluded that the substantial
risk of disease due to not vaccinating children far outweigh the
theoretical risk posed by vaccines that have a remote chance of containing
the BSE agent (see PHS statement in MMWR and
"Recommendations for the Use of Vaccines Manufactured with Bovine
Derived Materials” section of this web site for details)
What is being done to ensure the United States’ vaccine supply
is safe?
Also see above “What is FDA doing now to assure that companies
follow guidance, letters and PTC documents?” FDA and the other PHS
agencies believe that vaccines licensed for use in the US are safe and
effective. However, because even the perception of risk could have
negative consequences for the use of vaccines and because it is possible
to decrease the risk of an already safe product even further,
manufacturers of affected vaccines have agreed to change the source of
the bovine derived material used during production of the working seeds
and cell banks and for routine production (see "Recommendations for the
Use of Vaccines Manufactured with Bovine Derived Materials"
section of this web site for details).
When will vaccine manufacturers finish replacing cow-derived
materials in vaccines with materials obtained from countries free of BSE?
The time to make a vaccine and bring it to market can take several
months to a year. Most vaccine made using bovine derived material from
non-BSE risk countries should be available by the end of 2001.
Shouldn't all potentially contaminated vaccine be destroyed?
Also see above “Why is FDA leaving on the market vaccines which
may be contaminated with the BSE agent?” FDA and other PHS agencies
believe that the vaccines currently licensed for use in the US are safe.
A special joint meeting of the TSE and Vaccines and Related Biological
Products Advisory Committees concluded that the real risk of disease due
to not vaccinating far outweighs the theoretical risk posed by exposure
to vaccines that have a remote chance of containing the BSE agent.
Table of Contents
Last Updated: 3/29/2001
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