One of the greatest medical achievements of our time is at imminent risk of being undermined by bad science.
Thanks to a herculean effort by health advocates, 78 percent of children in low-income countries receive the basic set of childhood vaccines, covering diphtheria, tetanus, pertussis, hepatitis B and haemophilus influenzae. This campaign will be disrupted, and lives lost, if immunization critics win their latest battle for an international ban on a vaccine component that has proved to be safe time and time again.
Groups such as the Coalition for Mercury-Free Drugs and the Coalition for SafeMinds are pressing their case before the United Nations Environmental Program meets on Jan. 13 to prepare a global treaty reducing mercury use. One draft of the treaty bans the vaccine preservative thimerosol, a compound containing ethyl mercury. Vaccine critics have continued to link thimerosol to autism and other disorders, though the researcher who posited that connection in 1998 was found to have falsified the data, and no credible studies have replicated his result.
Those supporting the global ban say that with thimerosol no longer used in vaccines in the U.S., its continued inclusion in formulations meant for the developing world amounts to an injustice.
It’s true that in 1999, with parents claiming that vaccines had harmed their children, the Food and Drug Administration acted with an abundance of caution to ban most uses of thimerosol.
Since then, however, studies have shown that unlike other types of mercury, ethyl mercury is not absorbed by the body. And mounting evidence of the safety of thimerosol-containing vaccines has won them the support of the Global Advisory Committee on Vaccine Safety, the U.S. Institute of Medicine and the American Academy of Pediatrics.
Why not be extra cautious and remove thimerosol from global vaccines, just as it was taken out of U.S. doses? The answer is, doing so would disrupt supplies and make vaccines lethally expensive.
The need to package, ship and store vaccines contributes to their cost. Thimerosol reduces those expenses by enabling the production of some vaccines in multidose vials: The compound prevents bacterial and fungal contamination when a needle is repeatedly inserted into a bottle to withdraw doses.
Deployed in 120 countries to immunize 84 million children, vaccines containing thimerosol save the lives of an estimated 1.4 million people every year. The preservative is also used in wealthy countries for pandemic flu vaccines because multi-dose packaging facilitates rapid production and dissemination.
If thimerosol were banned, manufacturers could test other preservatives. However, the reformulated vaccines would have to go through new safety and efficacy testing before being approved, a process that can take a decade or more.
In the meantime, or alternatively, suppliers might package the relevant vaccines in single-dose vials. Vaccine makers would have to set up new production lines, which would raise manufacturing costs from 200 percent to 500 percent, according to recent estimates. During that time, output would cease.
Single-dose vials take up more space than their multidose equivalents, so the same amount of vaccine would require greater shipping and storage capacity. And because most of the affected vaccines must be chilled at a constant temperature, the costs and capacity issues are even greater.
Higher costs would mean fewer children vaccinated, which would mean more illness and death. India, for instance, aims to immunize all 25 million children born each year in the country with the essential pentavalent vaccine, now provided in a 10- dose vial at an average cost of $1.80 per immunization. With doses packaged individually costing about $1 more, the same budget for vaccines would leave 9 million kids unprotected against basic childhood illnesses. That would be the true injustice.
Vaccine critics have already invited the comeback of childhood disease in the U.S. by creating geographic clusters of unimmunized children. At the UNEP meeting, governments must stop this assault on progress by excluding ethyl mercury from any ban.