Report to WHO: No New Concerns About Thimerosal

Importantly, I found two studies regarding the use of the preservative 2-phenoxyethanol (2-PE) that call into question whether it is an acceptable alternative to thimerosal. One found that thimerosal is a superior preservative at 50 mcg/dose compared with 2-PE at 5 mg/dose in hepatitis B vaccines (Southeast Asian J. Trop. Med. Public Health 2010;41:876-82). The other found that while 2-PE was superior to thimerosal in inhibiting bacterial growth in the Prevnar 13 vaccine, it was less effective than thimerosal for controlling growth of Candida albicans or Aspergillus niger (Vaccine 2011;29:7144-53).

Alternative preservatives such as 2-PE have not been field tested, and therefore have not been proven to equal or surpass the proven preservative effectiveness of thimerosal. The potential risks of endorsing alternative preservatives such as 2-PE are unknown. Switching to single-dose vaccine vials adds about $1 per dose of each vaccine. That $1 is currently the cost of vaccinating a child with all of the current vaccines given in those countries, including pertussis, diphtheria/tetanus, hepatitis B, polio, measles, and Haemophilus influenzae B conjugate. It simply isn’t affordable or practical to do that. Not to mention unwise and unnecessary.

The United Nations is expected to vote on the environmental treaty this summer. The evidence suggests the 2008 endorsement of the use of thimerosal as a safe and effective preservative in vaccines for children worldwide should remain.

Dr. Pichichero, a specialist in pediatric infectious diseases, is director of the Rochester (N.Y.) General Research Institute. He is also a pediatrician at Legacy Pediatrics in Rochester. Dr. Pichichero said he received an honorarium to prepare this report from WHO and donated it to charity. All of his work on thimerosal in vaccines was supported by the National Institute of Allergy and Infectious Diseases. He said he has never received any payment from any vaccine or pharmaceutical company relating to thimerosal in vaccines or any product. He said he has received honoraria/consultant fees and his institution has received research grants from GlaxoSmithKline, Sanofi Pasteur, Pfizer, Novartis, and Crucell for new vaccine and product development, but none of these payments had any direct or indirect relationship to the evaluation of thimerosal in vaccines.