Last week’s announcement of the Minamata Convention on Mercury represents a huge step forward in international efforts to reduce the human health impacts of mercury. For GAVI what is most important about the global and legally-binding treaty is what was left out. The treaty made an exception for thiomersal, a mercury-based preservative that has been used in some vaccine manufacturing since the 1930s to prevent bacterial or fungal contamination of multi-dose vials of vaccine.
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The treaty exception represents a triumph of science over the politics of fear. The anti-vaccination lobby pressed hard to have thiomersal – known as thimerosal in the US – included in the treaty despite the scientific evidence that thiomersal poses no human health risk. Indeed, banning it would have disrupted vaccination programs in many developing countries, putting millions of children at risk from vaccine-preventable illness.
The anti-vaccine lobby has been successful in raising fears and doubts about the adverse effects of vaccination and the role of thiomersal in increases in developmental disorders and autism. With parents, scientists and even initially the American Academy of Pediatrics (AAP) weighing in, the United States implemented a precautionary reduction more than a decade ago. There is now a mountain of scientific evidence refuting any link between thiomersal and autism, and AAP reversed their 1999 position that called for elimination of mercury in vaccines. GAVI and AAP share a belief that scientific evidence should guide public policy, and the evidence on thiomersal is clear. It is a safe preservative used in multi-dose vaccines, and at this time there is no replacement for it. Good science and a good global policy.
At GAVI our goal is to reach the world’s poorest children with life-saving vaccines, and while we are pressing for innovations in vaccine delivery systems, the realities of the current cold chain and storage capacities in developing nations make multi-dose vaccines containing thiomersal a necessity. Without it the number of children receiving vaccines in in 120 countries, mostly in the developing world, would plummet. The World Health Organization estimates that thiomersal-containing vaccines avert at least 1.4 million child deaths every year by protecting children from fatal diseases, such as diphtheria, tetanus, and hepatitis B (1). By using multi-dose vaccines, we can reach more children, and we can save more lives.
It is encouraging to see that the treaty negotiators used good science to inform this important global policy. We need to build public confidence in vaccine safety, and reach the 22 million children who currently lack access to vaccines. As a doctor, an epidemiologist and a father, I know that childhood vaccination is a fundamental building block of health, and it gives me confidence to see that the treaty negotiators recognised that as well.
(1) The Lancet, Volume 379, Issue 9834, Page 2328, 23 June 2012