“Government representatives are meeting in Geneva this week to decide whether to introduce a global ban on mercury that could include thiomersal, a mercury-based preservative that has been used in some vaccine manufacturing since the 1930s to prevent bacterial or fungal contamination of multidose vials of vaccine,” Seth Berkley, a medical epidemiologist and chief executive of the GAVI Alliance, writes in a New York Times opinion piece. “Despite the ominous connotations of mercury, the decision should in theory be a no-brainer: The scientific and medical consensus is that thiomersal poses no human health risk, and that rather than saving lives, a ban would put millions of the world’s poorest children at risk of deadly diseases by disrupting vaccination programs,” he continues. Switching to single dose vials would be costly and impractical, and “[i]n the absence of any alternative preservative, far fewer vaccines would reach children in developing countries,” he states.

“But with vaccines, logic and evidence don’t always prevail,” Berkley writes, and he notes that in the 1990s, “[d]espite a lack of evidence that it was harmful — and in the absence of any evidence to show that it wasn’t — the FDA decided to take a precautionary approach and urged manufacturers to reduce or eliminate thiomersal from almost all vaccines in the United States,” unknowingly doing damage to the preservative’s reputation. Berkley recaps the ongoing debate on the issue, highlighting campaigns by anti-vaccination groups claiming the mercury derivative is responsible for increases in autism despite contrary evidence, and discusses the impact a ban on thiomersal would have on vaccination efforts in developing countries. He concludes, “With millions of vulnerable lives at stake, the treaty negotiators need to engage and recognize that a ban on thiomersal would be bad policy based on bad science” (1/17).