Notice to Readers: Summary of the Joint Statement on Thimerosal
in Vaccines
In June 2000, a joint statement on thimerosal* in vaccines was prepared by
the American Academy of Family Physicians (AAFP), the American Academy of
Pediatrics (AAP), the Advisory Committee on Immunization Practices (ACIP), and the
Public Health Service (PHS) in response to 1) the progress in achieving the national
goal declared in July 1999 to remove thimerosal from vaccines in the
recommended childhood vaccination schedule, and 2) results of recent studies that
examined potential associations between exposure to mercury in thimerosal-containing
vaccines and health effects. In this statement, AAFP, AAP, ACIP, and PHS
recommend continuation of the current policy of moving rapidly to vaccines that are free
of thimerosal as a preservative. Until adequate supplies are available, use of
vaccines that contain thimerosal as a preservative is acceptable.
A joint statement issued by AAP and PHS in July 1999 and agreed to by the
AAFP later in 1999 established the goal of removing thimerosal as soon as possible
from vaccines routinely recommended for infants. The goal was established as
a precautionary measure. No evidence existed of any harm caused by low levels
of thimerosal in vaccines. Public concern had been expressed about the health effects
of mercury exposure of any sort, and the elimination of mercury from vaccines
was considered a feasible means of reducing an infant's total exposure to mercury in
a world where other environmental sources of exposure are more difficult or
impossible to eliminate (e.g., certain foods).
Since July 1999, substantial progress has been made in removing thimerosal
from vaccines. As of March 2000, all U.S. children had access to hepatitis B vaccines that
do not contain thimerosal as a preservative. Beginning July 2000, only
single-dose thimerosal-free Haemophilus
influenzae type b vaccine will be produced in the
United States; previously manufactured multidose vials containing thimerosal still may be
in distribution. One diphtheria and tetanus toxoids and acellular pertussis vaccine
(DTaP) that does not contain thimerosal is available, and it is projected that additional
DTaP vaccines without thimerosal as a preservative will become available in early 2001.
On the basis of this progress, the most likely maximum amount of ethylmercury that
an infant may be exposed to from the routine vaccination schedule has been reduced
by 60%, from 187.5 µg to 75 µg. Measles-mumps-rubella, varicella, inactivated polio,
and pneumococcal conjugate vaccines have never contained thimerosal.
Research on the potential health effects of exposure to thimerosal is
continuing,
and findings will be monitored closely by PHS to determine whether any changes
in policy are needed. AAFP, AAP, and PHS, in consultation with the ACIP, reaffirm the
goal set in July 1999 to remove or greatly reduce thimerosal from vaccines as soon
as possible. On the basis of information from the Food and Drug Administration
and manufacturers, PHS projects that the United States will complete its transition to
a secure routine pediatric vaccine supply free of thimerosal as a preservative by the
first quarter of 2001.
The vaccination of children in much of the world will continue to require the use
of multidose vials because of cost, production, and storage capacity. Multidose
vials require a preservative to prevent microbial contamination after the vial is opened.
For multidose vials, manufacturers are encouraged to seek alternatives to thimerosal.
* Thimerosal is a derivative of ethylmercury and has been used as an additive to biologics
and vaccines since the 1930s because it is effective in killing bacteria and in preventing
bacterial contamination, particularly in opened, multidose containers. The full text of this
statement is available on the World-Wide Web at http://www.aafp.org/policy/camp/20.html,
http://www.aap.org/policy/jointthim.html, and http://www.cdc.gov/nip/vacsafe/concerns/thimerosal/joint_statement_00.htm. References to sites of non-CDC organizations on
the World-Wide Web are provided as a service to
MMWR readers and do not constitute or imply endorsement of these organizations or their programs by CDC or the U.S. Department
of Health and Human Services. CDC is not responsible for the content of pages found at
these sites.
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