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. 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.

Flaws and all meaning