Unreasonable doubt

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(This Opinion column ran on Nature’s website June 15, 2007. You can see the original post here.)
A ‘vaccine court’ case on autism could have disastrous consequences if people confuse its verdict with scientific consensus.vaccine-mercury

Why are there so many more cases of autism now than there were 30 years ago? It’s a question the best scientific minds have been unable to answer. But I’m afraid a US court now looking at that question may settle it on the basis of emotion rather than science.

The parents of thousands of autistic children think that the routine measles-mumps-rubella (MMR) vaccine and the mercury-based vaccine preservative called thimerosal damaged their healthy children’s brains and made them autistic — and they’re now suing the US government for damages. On Monday, three ‘special masters’ of the US Court of Federal Claims began hearing testimony in the first of nearly 5,000 such cases, some of which have been pending for years.

I sympathize with these parents and can understand their need to find a reason for their children’s suffering. But I trust in science, and I can’t ignore the fact that so many peer-reviewed studies — and every scientific panel entrusted with evaluating those studies — has come to the same conclusion: neither the MMR vaccine nor thimerosal is associated with autism.

Polio’s return traced to lapses in India

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(This article was #60 in Discover Magazine’s top 100 stories of 2006.)

In May a 39-year-old man in Namibia tested positive for poliovirus, marking the country’s first case in 10 years. Since then, the outbreak there has reached 20 confirmed cases.

This year 10 other formerly polio-free countries are once again battling the disease. Genetic sequencing has traced cases in five of the countries, including Namibia, to a polio strain in India, where the virus remains endemic. As of October 2006, a total of 358 cases have occurred in the poor, densely populated north Indian state of Uttar Pradesh alone, up from 29 in 2005.

The World Health Organization has taken India to task, saying its outbreak is endangering efforts worldwide to keep the disease at bay. To protect a high-risk community from polio, at least 95 percent of the children must be vaccinated; but in late 2005 and early 2006 the vaccination rates in Uttar Pradesh dipped to between 85 and 90 percent.

The Indian government, vowing to eliminate polio by 2007, has discussed a pilot project using an injectable vaccine in addition to oral drops. The injectable vaccine is thought to offer better protection against polio infection in children with diarrhea, which is common in the area.