At a congressional inquiry in Washington into autism, five of America's most senior public health officials have been grilled about whether vaccines might be causing what the government reform committee chairman, Dan Burton, called an "epidemic" of autism in children.
They were presented with a dossier of exhibits comprising copies of e-mails, confidential minutes of meetings and other incriminating documents, which one congressman, Dave Weldon, said amounted to evidence of a cover-up. The public health authorities knew of the possible health risks from mercury in vaccines years ago, the documents showed, and had an emergency plan to remove it.
A secret study by the Centers for Disease Control and Prevention (CDC), which was never published, showed children who had received vaccines containing thimerosal - a preservative that is almost 50 per cent mercury - were more than twice as likely to develop autism as children who had not.
The hearing, on 19 June, was part of an two-year investigation into a dramatic rise in autism in the United States, from one in 10,000 children reported ten years ago to one in 250 now.
The session was called to review research into possible causes of autism, including the MMR vaccine and mercury. Mercury, the most toxic substance humans are likely to be exposed to, is present in some vaccines, but not the MMR.
In Britain, too, we are witnessing a significant increase in the number of children diagnosed with autism, from one in 2,200 estimated by the National Autistic Society in 1988 - when the MMR vaccine was introduced - to one in 166 now.
Here, as in the US, a growing number of parents believe their children were born and developed normally, but became autistic and suffer the additional burden of a painful inflammatory bowel disorder, because of vaccines. Many are taking legal action against the manufacturers.
They will be using research that they claim supports their case, including studies by Dr Andrew Wakefield, a consultant gastroenterologist who first raised the possibility that the MMR vaccine may be a contributory cause of autism and bowel disease in children brought to his clinic at the Royal Free Hospital in London.
Wakefield has since been forced out of his job because government ministers and health advisers have criticised his research as "unscientific". But at the congressional inquiry in June, three other scientists presented research findings that partially supported Wakefield.
Dr Arthur Krigsman, of the New York University School of Medicine, has conducted tests on 43 autistic children. He found that 90 per cent of them had the same inflammatory bowel disorders as Wakefield reported.
Two of the researchers, Dr Vera Stejskal, professor of immunology at the University of Stockholm, and Dr Jeff Bradstreet, a paediatrician from Florida, put forward the hypothesis that, in some genetically predisposed children, an accumulation of mercury damages the brain and lowers immunity. This means that the body cannot cope with the three live viruses in the MMR vaccine, thus triggering autism.
In March, the British government announced a £2.5m research programme into possible causes of autism. But the minister responsible, Jacqui Smith, ruled out looking at whether MMR was implicated, because, she said, that had already been investigated. But not thoroughly. Not independently.
Next year, the British and American lawsuits begin. So far, all the available studies into whether mercury and/or MMR cause autism, have failed to prove a link. But they haven't disproved one either. We need a thorough, independent, public or parliamentary inquiry, along the lines of a US congressional hearing, to tell us about the possible hazards of the government's vaccination programme - and whether it is causing autism.
Rosie Waterhouse is a reporter on the Sunday Times Insight team