Autism spectrum disorder (ASD) refers to a range of conditions characterised by some degree of impaired social behaviour, communication and language, and a narrow range of interests and activities that are both unique to the individual and carried out repetitively.

ASDs begin in childhood and tend to persist into adolescence and adulthood. In most cases the conditions are apparent during the first 5 years of life.

Individuals with ASD often present other co-occurring conditions, including epilepsy, depression, anxiety and attention deficit hyperactivity disorder (ADHD). The level of intellectual functioning in individuals with ASDs is extremely variable, extending from profound impairment to superior levels.

Available scientific evidence suggests that there are probably many factors that make a child more likely to have an ASD, including environmental and genetic factors.

Available epidemiological data are conclusive that there is no evidence of a causal association between measles, mumps and rubella vaccine, and ASD. Previous studies suggesting a causal link were found to be filled with methodological flaws.

There is also no evidence to suggest that any other childhood vaccine may increase the risk of ASD. Evidence reviews of the potential association between the preservative thiomersal and aluminium adjuvants contained in inactivated vaccines and the risk of ASD strongly concluded that vaccines do not increase the risk of ASDs.

People with ASD are often subject to stigma and discrimination, including unjust deprivation of health care, education and opportunities to engage and participate in their communities.

People with ASD have the same health problems that affect the general population. Furthermore, they may have specific health-care needs related to ASD or other co-occurring conditions. They may be more vulnerable to developing chronic noncommunicable conditions because of behavioural risk factors such as physical inactivity and poor dietary preferences, and are at greater risk of violence, injury and abuse.

People with ASD require accessible health services for general health-care needs like the rest of the population, including promotive and preventive services and treatment of acute and chronic illness. Nevertheless, people with ASD have higher rates of unmet health-care needs compared with the general population. They are also more vulnerable during humanitarian emergencies. A common barrier is created by health-care providers’ inadequate knowledge of ASD and misconceptions.