The claim that vaccines cause autism is one of the most widespread vaccine myths, but its origin and the evidence since are clear.
The source has been discredited
The claim came from a 1998 study on the MMR vaccine. It was later found to be based on falsified data with serious conflicts of interest, was formally retracted by the journal, and its author lost his medical licence.
Large studies find no link
After the retraction, many countries ran large studies involving millions of children, comparing those who had the MMR vaccine with those who hadn't. They consistently found no difference in autism rates. The evidence is strong in both scale and consistency.
Why the myth persists
The early signs of autism usually become noticeable between roughly one and two years of age, close to when the MMR vaccine is given. That coincidence in timing makes it easy to assume cause and effect, but timing alone is not a link.
The value of MMR
Measles is highly contagious and can cause serious complications. The MMR vaccine effectively prevents measles, mumps and rubella, and is provided under the Hong Kong Childhood Immunisation Programme.