By Michelle Roberts
Health reporter, BBC News
Latest autism figures should dispel any fears about the MMR jab being linked to the condition, say experts.
The NHS Information Centre found one in every hundred adults living in England has autism, which is identical to the rate in children.
If the vaccine was to blame, autism rates among children should be higher because the MMR has only been available since the early 1990s, the centre says.
This is the first time the rate in adults has been evaluated.
Tim Straughan, chief executive of The NHS Information Centre, said: "This landmark report is the first major study into the prevalence of autism spectrum disorders among adults to be carried out anywhere in the world.
"While the sample size was small and any conclusions need to be tempered with caution, the report suggests that, despite popular perceptions, rates of autism are not increasing, with prevalence among adults in line with that among children.
"It also suggests that, among adults, rates of autism remain broadly constant across age groups.
"The findings do not support suggestions of a link between the MMR vaccine and the development of this condition."
A Department of Health spokesperson said: "There is no credible evidence to support the link between the MMR vaccine and autism.
"MMR vaccine has been used extensively and safely around the world for over 30 years and is the best way of protecting your child against measles, mumps and rubella."
Concern over the measles, mumps and rubella vaccine was sparked by a paper published in The Lancet in 1998 by Dr Andrew Wakefield.
This research has since been discredited.
But, until now, little was known about how autism affected people over the course of a lifetime.
The latest findings, based on nearly 7,500 adults, suggests that prevalence of autism spectrum disorder remains broadly level across all age bands.
While 1% of adults had an autism spectrum disorder, which includes autism and Asperger's syndrome, the rate for men was higher (1.8%) than for women (0.2%). This was in line with studies among child populations which show higher rates amongst boys.
And in line with recent report from the National Audit Office, the study also found many of these adults are failing to get the diagnosis and specialist help they need.
Mr Straughan said: "This does beg some questions about whether services, as currently configured, are meeting the needs of this group of people."
Mark Lever, chief executive of the National Autistic Society, said: "The NAS has long campaigned to raise awareness of the fact that services and support for adults with autism are woefully inadequate.
"This study gives us further evidence to demand that more vital support is put in place."
Care Services Minister Phil Hope said: "This study will feed into the first ever adult autism strategy, which we will publish at the end of this year.
"The strategy should kick-start radical improvements in services for all forms of autism."
People with autism spectrum disorder may suffer a range of problems, including difficulty interacting with other people and communicating their feelings.