A 3-year-old female came to clinic for her health supervision visit. The resident physician noted that the preschooler was due for her second Hepatitis A and Influenza vaccines.
Her mother said, “I know that most of the thimerosal has been taken out of the vaccines, but do they still have preservatives in them?” The resident stated that he wasn’t sure but would find out for the mother before ordering the vaccines.
When discussing the healthy child with his attending physician, the resident said that he wasn’t sure where to find the preservative information.
The attending physician offered several suggestions including checking the American Academy of Pediatrics RedBook®, looking at the package inserts that the nursing staff kept easily available where they prepared the vaccines, and also looking at the U.S. Food and Drug Administration’s website.
Together the resident and attending physician looked up information about thimerosal and also the other preservatives in currently licensed vaccines.
The Hepatitis A vaccine (Havrix®) contained 2-phenoxyethanol but the Influenza vaccine (FluMist®) did not. Both did not contain thimerosal.
The diagnosis of a healthy preschooler was confirmed by the attending physician. During the discussion about the preservatives, the mother decided to have her daughter receive both vaccines.
Preservatives in vaccines and other biological products are used to prevent growth or kill microorganisms especially bacteria and fungi that could accidentally contaminate the product prior to administration.
While preservatives can decrease the risk of contamination, especially in multi-dose vials, they cannot completely eliminate the risk.
Thimerosal has been used as a preservative for many years and is approximately 50% mercury by weight. It is metabolized into ethyl mercury and thiosalicylate. Ethyl mercury is an organomercurial that is related, but distinctive from, methylmercury.
Methylmercury is a known neurotoxin and most exposure comes through food.
Because of potential concerns about thimerosal as a preservative, especially neurocognitive concerns, manufacturers have decreased or eliminated thimerosal as a preservative in many vaccines and other biological agents.
The Institute of Medicine Immunization Safety Review Committee issued a report in 2004 which concluded that the evidence “??? favors rejection of a causal relationship between thimerosal-containing vaccines and autism, and that hypotheses generated to date concerning a biological mechanism for such causality are theoretical only. The committee also stated “???that the benefits of vaccination are proven and the hypothesis of susceptible populations is presently speculative, and that widespread rejection of vaccines would lead to increase in incidence of serious infectious diseases like measles, whooping cough and Hib bacterial meningitis.”
Preservatives used in vaccines licensed in the U.S.
- 2- Phenoxyethanol
- DTaP – Infranix by GlaxoSmithKline Biologicals
- Hepatitis A – Havrix by GlaxoSmithKline Biologicals
- Hepatitis A/Hepatitis B – Twinrix by GlaxoSmithKline Biologicals
- 2 -Phenoxyethanol and formaldehyde
- DTaP – Daptacel by Sanofi Pasteur, Ltd
- Inactivated Poliovirus – IPOL by Sanofi Pasteur, SA
- Benzethonium chloride (Phemerol)
- Anthrax – Biothrax by BioPort Corporation
- Pneumococcal Polysaccaride – Pneumovax 23 by Merck and Co., Inc.
- Typhoid Vi Polysaccaride – Typhim Vi by Sanofi Pasteur, SA
- Td – several manufacturers
- TT – several manufacturers
- Influenza – several manufacturers
Thimerosal-free vaccines for vaccines routinely recommended for children under 6 years of age
- Infanrix by GlaxoSmithKline Biologicals, thimerosal free since 9/29/2000
- Daptacel by Sanofi Pasteur, Ltd, never contained thimerosal
- DTaP-HepB-IPV – Pediarix by GlaxoSmithKline Biologicals, thimerosal free since 1/29/2007
- Hepatitis B
- Recombivax HB by Merck and Co, Inc., thimerosal free since 8/27/99
- Engerix B by GlaxoSmithKline Biologicals, thimerosal free since 1/30/2007
- Haemophilus influenza type b conjugate (HIB)
- ActHIB by Sanofi Pasteur, SA, never contained thimerosal
- OmniHIB by GlaxoSmithKline Biologicals, never contained thimerosal
- PedvaxHIB by Merck and Co, Inc., thimerosal free since 8/99
- HibTITER (single dose) by Wyeth Pharmaceutical Inc., never contained thimerosal
- Hib/Hepatitis B combination – Comvax by Merck and Co, Inc., never contained thimerosal
- Inactivated Poliovirus – IPOL by Sanofi Pasteur, SA, never contained thimerosal
- Influenza (inactivated)- Fluzone by Sanofi Pasteur, inc, thimerosal free since 12/23/2004
- Influenza (live) – FluMist by MedImmune Vaccines, Inc., never contained thimerosal
- Measles-Mumps-Rubella – M-M-R-II by Merck and Co, Inc., never contained thimerosal
- Pneumococcal conjugate – Prevnar by Wyeth Pharmaceutical Inc., never contained thimerosal
- Rotavirus – Rotateq by Merck and Co, Inc., never contained thimerosal
- Varicella – Varivax by Merck and Co, Inc., never contained thimerosal
Questions for Further Discussion
1. What other biological agents contain mercury as a preservative?
To Learn More
To view pediatric review articles on this topic from the past year check PubMed.
To view current news articles on this topic check Google News.
To view images related to this topic check Google Images.
U.S. Food and Drug Administration. Thimerosal in Vaccines.
Available from the Internet at http://www.fda.gov/cber/vaccine/thimerosal.htm#t1 (rev. 9/6/2007, cited 11/8/2007).
Immunization Action Coalition. Thimerosal in Vaccines.
Available from the Internet at http://www.vaccineinformation.org/thimerosal.asp (rev. 7/6/2007, cited 11/8/2007).
ACGME Competencies Highlighted by Case
1. When interacting with patients and their families, the health care professional communicates effectively and demonstrates caring and respectful behaviors.
2. Essential and accurate information about the patients’ is gathered.
3. Informed decisions about diagnostic and therapeutic interventions based on patient information and preferences, up-to-date scientific evidence, and clinical judgment is made.
4. Patient management plans are developed and carried out.
5. Patients and their families are counseled and educated.
6. Information technology to support patient care decisions and patient education is used.
8. Health care services aimed at preventing health problems or maintaining health are provided.
10. An investigatory and analytic thinking approach to the clinical situation is demonstrated.
11. Basic and clinically supportive sciences appropriate to their discipline are known and applied.
12. Evidence from scientific studies related to the patients’ health problems is located, appraised and assimilated.
13. Information about other populations of patients, especially the larger population from which this patient is drawn, is obtained and used.
14. Knowledge of study designs and statistical methods to appraisal clinical studies and other information on diagnostic and therapeutic effectiveness is applied.
15. Information technology to manage information, access on-line medical information and support the healthcare professional’s own education is used.
16. Learning of students and other health care professionals is facilitated.
17. A therapeutic and ethically sound relationship with patients is created and sustained.
18. Using effective nonverbal, explanatory, questioning, and writing skills, the healthcare professional uses effective listening skills and elicits and provides information.
19. The health professional works effectively with others as a member or leader of a health care team or other professional group.
Donna M. D’Alessandro, MD
Professor of Pediatrics, University of Iowa Children’s Hospital
December 10, 2007