Issue Number 94
July 8, 1999
CONTENTS OF THIS ISSUE
- CDC publishes "Thimerosal in
Vaccines: A Joint Statement of the American Academy of Pediatrics and the Public Health
Service"
- U.S. Surgeon General issues statement
on vaccine safety
- CDC answers questions on thimerosal
and vaccines
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(1)
July 8, 1999
CDC PUBLISHES "THIMEROSAL IN VACCINES: A JOINT STATEMENT OF THE AMERICAN ACADEMY OF
PEDIATRICS AND THE PUBLIC HEALTH SERVICE"
The Centers for Disease Control and Prevention (CDC) published the following statement,
"Thimerosal in Vaccines: A Joint Statement of the American Academy of Pediatrics and
the Public Health Service," in the July 9, 1999, issue of the MMWR as a "Notice
to Readers." The full text of the notice is reprinted as follows:
"The Food and Drug Administration (FDA) Modernization Act of 1997 called for FDA to
review and assess the risk of all mercury-containing food and drugs. In line with this
review, U.S. vaccine manufacturers responded to a December 1998 and April 1999 FDA request
to provide more detailed information about the thimerosal content of their preparations
which include this compound as a preservative. Thimerosal has been used as an additive to
biologics and vaccines since the 1930s because it is very effective in killing bacteria
used in several vaccines and in preventing bacterial contamination, particularly in opened
multidose containers. Some but not all of the vaccines recommended routinely for children
in the United States contain thimerosal.
"There is a significant safety margin incorporated into all the acceptable mercury
exposure limits. Furthermore, there are no data or evidence of any harm caused by the
level of exposure that some children may have encountered in following the existing
immunization schedule. Infants and children who have received thimerosal-containing
vaccines do not need to be tested for mercury exposure.
"The recognition that some children could be exposed to a cumulative level of mercury
over the first six months of life that exceeds one of the federal guidelines on methyl
mercury now requires a weighing of two different types of risks when vaccinating infants.
On the one hand, there is the known serious risk of diseases and deaths caused by failure
to immunize our infants against vaccine-preventable infectious diseases; on the other,
there is the unknown and probably much smaller risk, if any, of neurodevelopmental effects
posed by exposure to thimerosal. The large risks of not vaccinating children far outweigh
the unknown and probably much smaller risk, if any, of cumulative exposure to
thimerosal-containing vaccines over the first six months of life.
"Nevertheless, because any potential risk is of concern, the Public Health Service
(PHS), the American Academy of Pediatrics (AAP), and vaccine manufacturers agree that
thimerosal-containing vaccines should be removed as soon as possible. Similar
conclusions were reached this year in a meeting attended by European regulatory agencies,
European vaccine manufacturers, and FDA, which examined the use of
thimerosal-containing vaccines produced or sold in European countries.
"PHS and the AAP are working collaboratively to assure that the replacement of
thimerosal-containing vaccines takes place as expeditiously as possible while at the same
time ensuring that our high vaccination coverage levels and their associated low disease
levels throughout our entire childhood population are maintained.
"The key actions being taken are
- A formal request to manufacturers for a clear
commitment and a plan to eliminate or reduce as expeditiously as possible the
mercury content of their vaccines.
- A review of pertinent data in a public workshop.
- Expedited FDA review of manufacturers' supplements
to their product license applications to eliminate or reduce the mercury content of a
vaccine.
- Provide information to clinicians and public
health professionals to enable them to communicate effectively with parents and
consumer groups.
- Monitoring immunization practices, future
immunization coverage, and vaccine-preventable disease levels.
- Studies to better understand the risks and
benefits of this safety assessment.
"PHS and AAP continue to recommend that all
children should be immunized against the diseases indicated in the recommended
immunization schedule. Given that the risks of not vaccinating children far outweigh the
unknown and much smaller risk, if any, of exposure to thimerosal-containing vaccines over
the first six months of life, clinicians and parents are encouraged to immunize all
infants even if the choice of individual vaccine products is limited for any reason.
"While there is a margin of safety with existing vaccines containing thimerosal,
there are steps that can be taken to increase that margin even further. Clinicians and
parents can take advantage of the flexibility within the existing schedule for infants
born to hepatitis B surface antigen (HBsAg)-negative women to postpone the first dose of
hepatitis B vaccine from birth until two to six months of age when the infant is
considerably larger. Preterm infants born to HBsAg-negative mothers should similarly
receive hepatitis B vaccine, but ideally not until they reach term gestational age and a
weight of at least 5.5 lbs (2.5 kg). Because of the substantial risk of disease, there is
no change in the recommendations for infants of HBsAg-positive mothers or of mothers whose
status is not known. Also, in populations where HBsAg screening of pregnant women is
not routinely performed, vaccination of all infants at birth should be maintained, as is
currently recommended. In addition to the key actions mentioned above, the PHS Advisory
Committee on Immunization Practices and the AAP Committee on Infectious Diseases will be
reviewing these issues and may make additional statements."
END OF JOINT STATEMENT
To access the joint statement from the AAP website, click here: http://www.aap.org
To obtain a text version of the MMWR article, click here: http://www.cdc.gov/epo/mmwr/preview/mmwrhtml/mm4826a3.htm
To access this issue of the MMWR in camera-ready (PDF) format, click here: ftp://ftp.cdc.gov/pub/Publications/mmwr/wk/mm4826.pdf
HOW TO GET A FREE ELECTRONIC SUBSCRIPTION TO THE MMWR
To get a free electronic subscription to the MMWR (delivered weekly), go to the MMWR
website and sign up. When you sign up, you will also automatically begin to receive all
new ACIP statements which are published as MMWR's "Recommendations and Reports."
To get to the MMWR website, click here: http://www2.cdc.gov/mmwr/
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July 8, 1999
U.S. SURGEON GENERAL ISSUES STATEMENT ON VACCINE SAFETY
The Immunization Action Coalition received the following document from the Centers for
Disease Control and Prevention on July 8, 1999.
STATEMENT BY DAVID SATCHER, MD, PhD
U.S. Surgeon General
Assistant Secretary for Health
Department of Health and Human Services
"Vaccines, approved for use in the United States, have been protecting our nation's
children from deadly infectious diseases since our grandparent's generation. In fact,
vaccines can be credited for saving more lives and preventing more illnesses than any
medical treatment. Without question, continuing to ensure our children are vaccinated with
licensed vaccines is critical to protect their health and to prevent disease outbreaks.
FDA considers all vaccines currently available to be safe and effective.
"It is essential that children continue to receive all vaccines according to
currently recommended schedules. The risk of devastating childhood diseases like whooping
cough, bacterial meningitis, tetanus, polio and diphtheria is real.
"Physicians and parents should be reassured
that continuing to vaccinate infants, within the flexibility of today's schedule, is the
best way to protect infants from devastating childhood diseases. Although the United
States enjoys some of the lowest levels of disease, the disease causing organisms still
circulate among us. Terrible childhood diseases like whooping cough, bacterial meningitis,
polio, and diphtheria are waiting for us to let our guard down. The risk of devastating
childhood diseases from failure to vaccinate far outweighs the minimal, if any, risk of
exposure to cumulative levels of mercury in vaccines. The choice to vaccinate infants with
these vaccines is a sound one."
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(3)
July 8, 1999
CDC ANSWERS QUESTIONS ON THIMEROSAL AND VACCINES
On July 8, 1999, the Centers for Disease Control and Prevention (CDC) published the
following set of questions and answers regarding thimerosal and vaccines on their
website:
Q 1. What is Thimerosal?
A. Thimerosal is a very effective preservative that contains mercury and has been used in
some vaccines and other products since the 1930s. Thimerosal is the most widely used
preservative in vaccines. The FDA estimates that it is used in more than 30 licensed
vaccines and biologics. Mercury is excreted from the body over time.
Q 2. Why is Thimerosal used in vaccines?
A. Thimerosal is used as an extra safeguard against contamination. It may be used during
processing or added to the final container to prevent contamination when multi-dose vials
are opened. Before Thimerosal was marketed in the United States, a number of safety
studies were conducted, first on animals and then on humans. Thimerosal is an important
preservative that protects vaccine against bacterial contamination. It is very effective
in killing bacteria used in several vaccines and in preventing bacterial contamination,
particularly in opened multi-dose containers. Some but not all of the vaccines recommended
routinely for children in the United States contain thimerosal. Disease outbreaks have
occurred following contamination of multi-dose vaccine vials in the United States and from
other countries. For example, in April, 1995, three infants died in India from toxic shock
syndrome after administration of contaminated measles vaccine at one health center.
Q 3. Can all vaccines be made Thimerosal-free, or within accepted guidelines? If so, how
quickly?
A. All vaccines either do not contain thimerosal or contain thimerosal within FDA
guidelines. To further increase the margin of safety that already exists, clinicians can
use the inherent flexibility in the current immunization schedule to fully vaccinate
children and meet even the most conservative guidelines for cumulative mercury exposure.
Clinicians and parents can take advantage of the flexibility within the existing schedule
for infants born to Hepatitis B surface antigen (HbsAg)-negative women to postpone
the first dose of hepatitis B vaccine from birth until two to six months of age when
the infant is considerably larger. Pre-term infants born to HBsAg-negative mothers should
similarly receive hepatitis B vaccine, but ideally not until they reach term gestational
age and a weight of at least 2.5 kilograms. Because of the substantial risk of
disease, there is no change in the recommendations for infants of HbsAg-positive mothers
or of mothers whose status is not known. Also, in populations where HbsAg screening
of pregnant women is not routinely performed, vaccination of all infants at birth
should be maintained, as is currently recommended. Public Health Service agencies are
working with private physician groups and vaccine manufacturers to expedite the process to
reduce or eliminate thimerosal from vaccines used in the United States.
Q 4. What could happen if parents ignored recommendations to use
thimerosal-containing vaccines during this transition period?
A. Children would be at very real risk from illnesses that can be prevented with
safe and effective vaccinations. High rates of vaccination led to declines of 95% to
100% in the occurrence of vaccine preventable diseases in the United States. Despite
this, the pathogens responsible for most vaccine preventable diseases still circulate and
rates of disease would increase if vaccine coverage dropped. For example, if vaccination
coverage among infants dropped from 95% to 70%, an additional 2,500 cases of pertussis
would be expected to occur. Moreover, the risk of death from pertussis is greatest in
young children. A second severe vaccine preventable disease among young children is
Haemophilus influenzae type b (Hib). Before vaccine was introduced, this pathogen was the
leading cause of meningitis and other severe invasive infections among children; now cases
of invasive Hib disease have virtually disappeared. If vaccination for Hib declined to
70%, 2,000 excess cases would occur with 1,200 cases of meningitis, resulting in about 100
deaths and 180 children who would suffer mental retardation and hearing loss.
Q 5. Why isn't the federal government just recommending not using vaccines with thimerosal
in them if there is concern?
A. Making vaccines safer and more effective is a constant goal for the federal government;
and, that is the purpose of the action we're taking now. There is a significant
safety margin incorporated into all acceptable mercury exposure limits. Furthermore,
there are no data or evidence of any harm caused by the level of exposure that some
children may have encountered in following the existing immunization schedule.
Today, we're discussing a minimal, if any, risk from minute levels of
mercury-containing thimerosal versus the large and devastating risk of childhood diseases
like bacterial meningitis and whooping cough if parents and physicians abandon vaccination
during this transition period. Any missed vaccinations puts children at risk from
disease.
Q 6. How much mercury did my 6-month-old get in
the last six months from vaccines? How dangerous is that?
A. Each dose of vaccine given your child met FDA requirements and should not be a concern
to you now--your choice to vaccinate your baby was a sound one. The mercury levels being
discussed are well within the safety margins; however, we are working toward further
increasing the margin of safety that already exists. It is important that we limit the
cumulative amount of mercury children are exposed to, but parents should not abandon
vaccination as a means to do that.
Q 7. If there are vaccines that are mercury-free, why shouldn't I just ask for those?
A. The American Academy of Pediatrics, the Advisory Committee on Immunization
Practices for CDC and the Surgeon General all recommend that parents do not let their
child miss a vaccination when safe and effective vaccines are available. Today, we are
discussing a minimal, if any, risk from cumulative levels of mercury from some vaccines
versus the large and devastating risk of childhood diseases like bacterial meningitis and
whooping cough if parents and physicians abandon vaccination during this transition
period.
Clinicians and parents can take advantage of the
flexibility within the existing schedule for infants born to Hepatitis B surface antigen
(HbsAg)-negative women to postpone the first dose of hepatitis B vaccine from
birth until two to six months of age when the infant is considerably larger.
Pre-term infants born to HBsAg-negative mothers should similarly receive hepatitis B
vaccine, but ideally not until they reach term gestational age and a weight of at least
2.5 kilograms. Because of the substantial risk of disease, there is no change in the
recommendations for infants of HbsAg-positive mothers or of mothers whose
status is not known. Also, in populations where HbsAg screening of pregnant women is
not routinely performed, vaccination of all infants at birth should be maintained, as is
currently recommended. Public Health Service agencies are working with private physician
groups and vaccine manufacturers to expedite the process to reduce or eliminate thimerosal
from vaccines used in the United States.
The American Academy of Pediatrics, the Advisory Committee on Immunization Practices
for CDC and the U.S. Surgeon General want parents to be fully informed about
children's vaccines and if you have questions or concerns, we encourage you to speak to
your child's trusted health care provider.
Q 8. I've heard that children may be getting toxic levels of mercury from vaccines. Is
that true?
A. Everyone is exposed to mercury, even in some foods and household products. As
part of an ongoing assessment of mercury in the environment and in products, many
agencies have developed guidelines for acceptable levels of mercury--levels many
times below any amount known to cause harm. Some children, depending on which
vaccines they receive and the timing of those vaccines, are exposed to cumulative
levels of mercury close to the safety ranges of guidelines. To further increase this
margin of safety, clinicians and parents can take advantage of the flexibility within the
existing immunization schedule. It's important to understand that these highest acceptable
levels include a "safety cushion" to take into account all the variables that
people face in their exposures to mercury. No children are getting toxic levels of mercury
from vaccines.
Q 9. Are there vaccines available to prevent childhood diseases without exposing
them to mercury?
A. Yes, although you may discover that these vaccines are not immediately available from
your health care provider. The American Academy of Pediatrics, the Advisory Committee on
Immunization Practices for CDC and the Surgeon General all recommend that parents do not
let their child miss a vaccination when safe and effective vaccines are available. Today,
we have a minimal, if any, risk from minute levels of mercury-containing thimerosal in
some vaccines versus the large and devastating risk of childhood diseases like bacterial
meningitis and whooping cough if parents and physicians abandon vaccination during this
transition period. The American Academy of Pediatrics, the Advisory Committee on
Immunization Practices for CDC and the U.S. Surgeon General want parents to be fully
informed about children's vaccines and if you have questions or concerns, we encourage you
to speak to your child's trusted health care provider.
Q 10. Why are the Public Health Service and AAP making these recommendations now?
A. Although mercury is found in the environment,
in food and in household products, exposure to mercury is of concern and, when possible,
should be avoided. The Public Health Service agencies, the American Academy of Pediatrics,
and vaccine manufacturers agree that thimerosal should be reduced or eliminated in
vaccines to make already safety vaccines even safer and to allow for new vaccines to be
added to the schedule in the future. Some children, depending on which vaccines they
receive and the timing of those vaccines, are exposed to cumulative levels of mercury
close to the safety ranges of guidelines. The mercury levels being discussed are within
the safety margins; however, we are working toward further increasing the margin of safety
that already exists. It is important that we limit the cumulative amount of mercury
children are exposed to, but parents should not abandon vaccination as a means to do that.
Q 11. Why are chemicals and other substances added to vaccines?
A. Many things in today's world, including foods and medicines, have chemicals added
to them to prevent the growth of germs and reduce spoilage. Chemicals are added to
vaccines for similar reasons, to inactivate a virus or bacteria and to stabilize it,
helping to preserve the vaccine and prevent it from losing its potency over time.
Some additives are used in the production of vaccines. Vaccines may include suspending
fluid (e.g., sterile water, saline, or fluids containing protein); preservatives and
stabilizers (e.g., albumin, phenols, and glycine); and adjuvants or enhancers that help
the vaccine improve its immunogenicity (ability to protect against disease).
Q 12. I understand some people are sensitive to thimerosal and must avoid it. Do they have
problems with thimerosal-containing vaccines?
A. Most patients do not develop reactions to thimerosal given as a component of
vaccines even when they've had a patch or intradermal tests for thimerosal that
indicated hypersensitivity. Hypersensitivity to thimerosal usually consists of
local, delayed reactions.
Q 13. How can I find out what chemical additives are in specific vaccines?
A. Ask your health care provider or pharmacist for a copy of the vaccine package insert.
The package insert lists ingredients in the vaccine and discusses any known adverse
reactions.
Q 14. What is mercury?
A. Mercury is a chemical element. As such it is neither created nor destroyed -- the
same amount of mercury has existed since the earth was formed. Mercury is toxic to humans
and wildlife. Organic forms of mercury are the forms of mercury to which humans and
wildlife are generally exposed, usually from eating fish which have accumulated mercury in
their muscle tissue. Uses and releases of mercury have been reduced very
substantially in recent decades in the U.S. and most other industrialized countries.
Q 15. Who is most vulnerable to mercury?
A. Two groups are most vulnerable to methyl mercury: the fetus and children ages 14
and younger. Children may be at higher risk of mercury exposure than are adults
because they eat more per pound of body weight and because they may be inherently more
sensitive than adults since their nervous systems are still developing.
Q 16. Which population groups have the highest levels of mercury?
A. Groups that tend to have higher exposure include subsistence and frequent recreational
fishers, people of Asian origin, and some Native American groups. The typical U.S.
consumer eating fish from restaurants and grocery stores are not in danger of
consuming harmful levels of mercury from fish and are not advised to limit fish
consumption. Everyone is exposed to mercury, even in some foods and household products.
Q 17. How can parents learn more about children's immunizations?
A. To learn more about children's immunizations, vaccinations, or baby shots from a CDC
information specialist, please call CDC's National Immunization Information Hotline:
1-800-232-2522, for English, 1-800-232-0233, for Spanish.
This set of questions and answers is available on CDC's website at: http://www.cdc.gov/nip/Q&A/genqa/Thimerosal.htm
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