Pediatricians: Keep Thimerosal in Vaccines

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Regardless

of how you might feel about

vaccines in general, be aware that Thimerosal

"can

still be found in some seasonal influenza vaccines and other adult

vaccines."

***

http://www.medpagetoday.com/InfectiousDisease/Vaccines/36480

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The American Academy of Pediatrics has endorsed the

World Health Organization's stance that thimerosal, a

mercury-based preservative, should be left in vaccines

and should not be subject to a ban contained in a

draft treaty from the United Nations Environment

Program (UNEP).

Note that thimerosal allows the use of multiuse

vials, and that a thimerosal ban could threaten access

to certain vaccines, such as tetanus toxoid,

diphtheria-tetanus-whole cell pertussis, and hepatitis

B vaccines, around the world.

The American Academy of Pediatrics has endorsed the World

Health Organization's stance that thimerosal -- a mercury-based

preservative -- should be left in vaccines and should not be

subject to a ban contained in a draft treaty from the United

Nations Environment Program (UNEP).

In a brief statement published online in Pediatrics,

the academy supported the recommendations drafted by the WHO's

Strategic Advisory Group of Experts (SAGE) on immunization at an

April meeting. An AAP spokesperson said that the endorsement was

adopted unanimously by the academy's infectious diseases

committee.

The Pediatrics Infectious Diseases Society and the

International Pediatric Association have also thrown their

support behind the guidance.

In 2009, UNEP requested that an Intergovernmental Negotiating

Committee develop a binding treaty to reduce the hazards of

environmental mercury. Included in the draft treaty, which will

be debated and possibly finalized next month, is a provision

banning the use of thimerosal in vaccines.

The WHO has called for the removal of that provision, with SAGE

concluding that although it supports efforts to reduce

environmental mercury, "it is essential that access to

thimerosal-containing vaccines is not restricted under this

global initiative."

An Evolving Position on Thimerosal

Thimerosal has been used to prevent the growth of bacteria and

fungi in multidose vials of vaccines since the 1930s. In recent

decades, concerns have been raised about the potential

neurotoxic effects of the preservative and a possible

association with autism because it contains mercury in the form

of organic ethyl mercury.

The FDA tackled the issue in the late 1990s, and its review

showed that the cumulative amount of mercury from vaccines

included in the routine immunization schedule for infants could

exceed the safety threshold set by the U.S. Environmental

Protection Agency based on studies of inorganic methyl mercury.

The amount did not, however, rise above the thresholds

established by federal guidelines from the Agency for Toxic

Substance Disease Registry and the FDA.

Based on those findings, and in addition to growing public

pressure driven by congressional hearings and increasing media

attention on potential adverse neurodevelopmental effects of

thimerosal, the AAP and the U.S. Public Health Service (USPHS)

in 1999 called for the removal of mercury from all vaccines.

"Once the FDA calculations revealed that even one federal

guideline was exceeded, the AAP and USPHS were obligated to full

public disclosure," explained Louis , MD, of Columbia

University in New York City, and Katz, MD, of Duke

University in Durham, N.C., in a commentary accompanying the

academy's current endorsement.

"With that disclosure, it was important to demonstrate a

response that could prevent exceeding the guideline levels and

also to continue to protect infants by still ensuring full

immunization," wrote , a member of the AAP board of

directors in 1999, and Katz, a former chair of the academy's

infectious diseases committee. "The joint statement met those

obligations while demonstrating an abundance of caution: putting

safety first."

By 2001, thimerosal had been removed from most vaccines in the

U.S. and other high-income countries; it can still be found

in some seasonal influenza vaccines and other adult vaccines.

In areas of the world with fewer resources, however, thimerosal

is still widely used as a vaccine preservative.

At the time of the joint statement by the AAP and USPHS, there

were no studies that had evaluated the potential harm of ethyl

mercury -- as opposed to its inorganic counterpart, methyl

mercury -- obtained through vaccines.

Since then, however, studies looking for harms from

thimerosal-containing vaccines have failed to find such associations, whereas

research has consistently demonstrated serious neurotoxic

effects from methyl mercury.

The consistent lack of evidence of any harm from thimerosal in

vaccines formed the basis of the AAP's reversal of its 1999

stance, and and Katz suggested that the academy would not

have issued the original statement with than knowledge in-hand.

Potential Fallout from a Thimerosal Ban

In another commentary, Walter Orenstein, MD, of Emory

University in Atlanta, and colleagues explained the benefits of

keeping thimerosal as an option for vaccines.

"Thimerosal allows the use of multiuse vials, which reduce

vaccine cost and the demand on already constrained cold-chain

systems," they wrote.

They said banning use of the preservative could harm the

world's vaccine supply by increasing manufacturing costs,

reducing manufacturing capacity because of the need to switch to

single-dose vials, increase waste from single-dose packaging,

and strain transportation and storage space.

"The resulting cold-chain requirements would be untenable in

many areas of the world because of programmatic challenges and

increased workload," Orenstein and colleagues wrote.

"The continued benefits of thimerosal use in vaccine

manufacturing clearly outweigh any perceived risks," they added.

In its recommendations, the WHO's SAGE noted that there are no

viable alternatives to thimerosal.

"Replacement of thimerosal with an alternative preservative may

affect the quality, safety, and efficacy of vaccines;

re-registration would be required by the National Regulatory

Authority in each jurisdiction where a reformulated product was

intended to be used; currently available alternative

preservatives interacted in unpredictable ways with existing

vaccines, and there are no consensus alternative preservatives

for the near- or mid-term," according to the guidance.

Ultimately, it stated, a thimerosal ban could threaten access

to certain vaccines -- such as tetanus toxoid,

diphtheria-tetanus-whole cell pertussis, and hepatitis B

vaccines -- around the world, particularly in developing

countries.

"There would be a high risk of serious disruption to routine

immunization programs and mass immunization campaigns if

thimerosal-preserved multidose vials were not available for

inactivated vaccines, with a predictable and sizable increase in

mortality, for exceedingly limited environmental benefit," the

statement read.

In a third commentary, King, PhD, of St. 's

Hospital in Toronto, and colleagues noted that "some

nongovernmental organizations oppose [removing the ban on

thimerosal from vaccines from the draft treaty], arguing that it

would be unjust to allow thimerosal to be used in low- and

middle-income countries when its use has been all but phased out

of wealthier nations."

"This critique is misplaced," they wrote, adding that there is

no threat of injustice because of the lack of evidence of health

risks.

"Rather," they wrote, "the real threat of injustice comes from

considering the removal of this currently necessary and

irreplaceable compound from the global vaccine supply, and the

avoidable increases in morbidity and mortality that would

inevitably result from disruptions to vaccination programs

targeting already marginalized populations in low- and

middle-income countries."

All authors of the AAP's statement of endorsement have filed

conflict of interest statements. Any conflicts have been

resolved through a process approved by the academy's board of

directors. The AAP said it has neither solicited nor accepted

any commercial involvement in the development of the content

of the statement.

and Katz reported that they had no conflicts of

interest.

King and colleagues reported that they had no conflicts of

interest.

Orenstein and colleagues reported that they had no conflicts

of interest.

Primary source: Pediatrics

Source reference:

L, Katz S. "Ban on thimerosal in draft treaty on

mercury: why the AAP's position in 2012 is so important" Pediatrics

2013;131:152-153.

Additional source: Pediatrics

Source reference:

AAP. "Statement of endorsement: recommendation of WHO

Strategic Advisory Group of Experts (SAGE) on immunization" Pediatrics

2012.

Additional source: Pediatrics

Source reference:

King K, et al. "Global justice and the proposed ban on

thimerosal-containing vaccines" Pediatrics

2013;131:154-156.

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