The United Nations Environment Programme has been drafting a global treaty to rid the world of the threats posed by mercury. As part of these discussions, proposals were made to restrict vaccines that contain the preservative thiomersal, a mercury-based preservative that has been used in some vaccine manufacturing since the 1930s to prevent contamination of multidose vials of vaccine. After a concerted effort by development partners, the final text, which will be ratified in October this year, now ensures that thiomersal can continue to be used in vaccines.
The World Health Organisation has said that “thiomersal-containing vaccines [are] safe, essential, and irreplaceable components of immunization programs, especially in developing countries, and…removal of these products would disproportionately jeopardize the health and lives of the most disadvantaged children worldwide.”
As Seth Berkley, CEO of the GAVI Alliance, pointed out in the New York Times last week, “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.” The science surrounding this issue has become unnecessarily clouded in recent decades. This is in part due to the efforts of anti-vaccination groups, as is pointed out by Dr Berkley.
Using this preservative is especially important in developing countries. Single dose vaccine vials are more expensive, and are less practical when health workers want to immunise large numbers of children. They also take up more space in refrigerators, subsequently limiting ‘cold chain’ capacity further (to read more about this issue, read our blog from July).
In 2010 alone it is estimated that more than 1.4 million child deaths were prevented through the use of thiomersal-containing vaccines. Today vaccines are saving millions of lives every year, with coverage rising steadily over recent decades. This restriction would have jeopardized much of that progress. A job well done by those who saw off this threat.