Laboratories that work with natural measles virus (such as the lab where these studies were performed) are at high risk of getting results that are incorrectly positive.
The method used to detect measles virus in these studies was very sensitive. 
Although methods are available to distinguish these two types of virus, the authors chose not to use them.
Because natural measles virus is still circulating in England, it would have been important to determine whether the measles virus detected in these samples was natural measles virus or vaccine virus. Although this information was clearly available to the investigators and critical to their hypothesis, it was specifically omitted from the paper. Second, children must be matched for the length of time between receipt of MMR vaccine and collection of biopsy specimens. First, children with or without autism must be matched for immunization status (i.e., receipt of the MMR vaccine). Therefore, children with or without autism must be identical in two ways. To determine if MMR is associated with autism, one must determine if the finding is specific for children with autism. Because all APCs are mobile, and can travel throughout the body (including the intestine), it is plausible that a child immunized with MMR would have measles virus detected in intestinal tissues using a very sensitive assay. Measles vaccine virus is likely to be taken up by specific cells responsible for virus uptake and presentation to the immune system (termed antigen-presenting cells or APCs). After inoculation, the vaccine virus probably replicates (or reproduces itself) about 15 to 20 times. Measles vaccine virus is live and attenuated. However, the second Wakefield paper was also critically flawed for the following reasons: On its surface, this was a concerning result. Seventy-five of 91 children with autism were found to have measles virus in intestinal biopsy tissue as compared with only 5 of 70 patients who didn't have autism. The authors tested intestinal biopsy samples for the presence of measles virus from children with and without autism. In 2002, Wakefield and coworkers published a second paper examining the relationship between measles virus and autism. In this case, the studies were deemed fraudulent and data misrepresented. This study was subsequently retracted in scientific terms, this means that the paper is not part of the scientific record because it was found to be based on scientific misconduct. Although the authors claim that autism is a consequence of intestinal inflammation, intestinal symptoms were observed after, not before, symptoms of autism in all eight cases. However, determination of whether MMR causes autism is best made by studying the incidence of autism in both vaccinated and unvaccinated children. The observation that some children with autism recently received MMR is, therefore, expected. Because MMR is administered at a time when many children are diagnosed with autism, it would be expected that most children with autism would have received an MMR vaccine, and that many would have received the vaccine recently. About 90% of children in England received MMR at the time this paper was written. The Wakefield paper published in 1998 was flawed for two reasons: 
All of these children had intestinal complaints and developed autism within one month of receiving MMR. Wakefield described 12 children with developmental delay - eight had autism.
#Infographic show innacurate series#
Wakefield's hypothesis was that the measles, mumps and rubella (MMR) vaccine caused a series of events that include intestinal inflammation, entrance into the bloodstream of proteins harmful to the brain, and consequent development of autism. In 1998, Andrew Wakefield and colleagues published a paper in the journal Lancet.
Two studies have been cited by those claiming that the MMR vaccine causes autism.
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