A huge row began in 1998. when the British medical journal The Lancet published a paper suggesting that there was a link between vaccination against measles, mumps and rubella (MMR) and autism. The work inadvertently sparked a controversy leading to a collapse in UK's vaccine programme. Six years later the journal was forced to retract the disputed part of the paper. Now Richard Horton, editor of the journal, explains why he accepted the paper and why he now feels he should have rejected it.

Horton retraces the intensity of the emotion evoked, following the publication in great detail. He examines the safety of the MMR vaccine and the rare complications that, unlike autism, have been proved to be due to the vaccination. He concludes that the available evidence shows the vaccine is very safe.

The MMR controversy did, however, reveal the inadequacy of the way in which vaccines were evaluated for safety. Horton ends the book with a lively discussion of how the media present scientific controversies, and the corrosion of public trust in science, scientists and authorities.