After their initial study, the Royal Free team went on to find similar gut abnormalities in a group of children with autism (Lancet, 1998; 351: 637-41). Of 48 children who'd developed autism just after vaccination, 46 exhibited these same bowel abnormalities. In Wakefield's view, the sheer number of children showing up with this particular bowel disorder and autistic tendencies coming on so soon after the vaccine was given is more than can be accounted for by chance.

Wakefield and Shattock postulate that the attenuated strain of the measle virus promotes an immune response insufficient to control the virus. As a result, a weakened 'infection' of sorts is established in the intestines and produces this increased permeability of the gut wall as well as the abnormal increase in the number of cells in the tissues.Urine tests showed that all the children had marked B12 deficiencies, as seen in other gastrointestinal disorders. Since B12 is necessary for the normal development of the central nervous system, Wakefield speculates that the B12 deficiency may be a contributory factor in the autistic regression seen in these children.

Besides Wakefield's research which is ongoing there is also anecdotal evidence from families. Of some 2500 families who have contacted the vaccine damage parent group JABS and the solicitors Alexander and Co, seeking compensation for vaccine damage, at least half these cases concern children who were developing normally, but then became autistic soon after vaccination. Furthermore, autism as a side effect is reported twice as often as any other serious side effect of the MMR.