John Walker-Smith, a coauthor of Wakefield's report and a supporter of the MMR vaccine, wrote in 2002 that epidemiology has shown that MMR is safe in most children, but observed that epidemiology is a blunt tool and studies can miss at-risk groups that have a real link between MMR and autism.[49] However, if a rare subtype of autism were reliably identified by clinical or pathological characteristics, epidemiological research could address the question whether MMR causes that autism subtype.[50] There is no scientific evidence that MMR causes damage to the infant immune system, and there is much evidence to the contrary.[3]