Autism or Measles?
A rational person would still vaccinate their children. Here's why:
The Risk is LowFirstly, the risk is still pretty low. Some estimates put the rate of autism at 1 out of 88 children. This is a little over 1%. In other words, even if vaccines cause most or all cases of autism, around 99% of vaccinated children will not get autism. And this is not just the risk from one vaccine. This is the risk among children who get all the recommended vaccines. Either there's only one or a few vaccines that cause autism and the others are safe, or the risk from any one vaccine is pretty miniscule indeed.
Admittedly, if you live in a high-vaccination country, your child's risk of being exposed to many of these illnesses is also low. It will also vary, depending on how many people in your social group visit countries with low vaccination rates, and the actual percentage of immune people in your social circle. It's especially high if your child decides to travel themselves, or if you take them travelling with you.
It's Not Just Your RiskIf your child suffers an adverse reaction to vaccines, they're the only one who'll get sick. But if you leave them unvaccinated and they get a vaccine-preventable viral illness, they could potentially spread it to anyone in contact with them.
Even in a high-vaccination country, not everyone will be immune. Some children are too young to have been vaccinated yet (for example, less than 18 months for the MMR). Some people have medical problems that mean they can't handle and/or won't benefit from vaccination, such as immune disorders. And some were vaccinated, but failed to develop immunity or lost their immunity later on (no vaccine is 100% effective).
With many illnesses, you could even spread it before you know you're infected. For example, a person infected with measles is contagious for four days before the rash appears. Even if you get prompt diagnosis, you might already have transmitted measles to someone in your social circle. If you get a delayed diagnosis, you could be contagious for up to four days after the rash appears, as well. Measles is transmitted as easily as any cold, if not more easily. When you talk, sneeze or cough, you'll leave virus in the air that can linger for up to two hours afterwards. (So you could even transmit it to someone without meeting them!)
If it were only parents of autistic kids who were afraid of vaccinating their children, this wouldn't be that big an issue. Younger siblings of autistic kids are a pretty small proportion of the population. But anti-vaccine parents are often quite open in expressing the belief that their child's autism was caused by vaccines, and many of them also over-emphasize the negatives of autism as well. Many people in their social circle may choose not to vaccinate on their recommendation. Worse yet, there are people talking publicly about vaccines causing autism, in some cases leading to people who've never even met an autistic person avoiding vaccination. We know that even if vaccines do cause autism, close to 99% of children can be vaccinated without getting autism. It's completely unnecessary for these people to avoid vaccination, and the lower the percentage of immunity in a population, the greater the risk of an epidemic.
Some of These Diseases Cause Autism TooIf vaccines can cause autism, you may reduce your risk of autism by not vaccinating. But you won't eliminate it, because vaccine-preventable illnesses have also been linked to autism.
For example, the MMR vaccine protects from three diseases - measles, mumps and rubella. All three of those diseases can cause autism.
The strongest link is with rubella. A child or adult who gets rubella will generally suffer only mild symptoms - flu-like symptoms as well as a rash - and many people don't even notice that they've been infected. However, if a woman gets rubella during the first 20 weeks of pregnancy (possibly even before she knows she's pregnant), her child can develop congenital rubella syndrome.
Unlike rubella, congenital rubella syndrome is quite prominent. The classic triad consist of deafness, eye abnormalities and heart defects. In addition, children can develop a wide range of other symptoms, including mental retardation and autism. So if you don't vaccinate your daughter against rubella, you could have a grandchild who is autistic due to congenital rubella syndrome.
Both measles and mumps can develop into viral meningitis or encephalitis. Meningitis refers to an infection of the mesh surrounding the brain, while encephalitis refers to an infection of the brain itself. Both of these complications can be fatal, and if the patient survives, they could suffer permanent brain injury. In addition to blindness, cerebral palsy, seizures, mental retardation and learning disabilities, autism is also a potential effect of this brain damage.
Autism is Not Worse Than DeathMany of these vaccine-preventable illnesses can be fatal. And this, alone, should mean that we'd take autism over those illnesses. But unfortunately, the idea that disabled people are better off dead didn't go away with the end of formal eugenics movements.
Because autism is the tail end of a bell curve, the majority of autistic people are mildly affected. Mild autism means struggling with social skills, and potentially with anxiety, executive functions, sensory processing and/or specific academic areas, but having a normal IQ and certain areas of strength. Many people in this range are highly successful, by many of the conventional standards of success. There are professors with mild autism, for example.
And secondly, even severe autism does not mean a pointless life. If given the right accommodations, a nonverbal child in diapers has as much potential for a happy life as anyone else. They can love and be loved and they can have fun. And that's what matters most. If you can do that, there is no way you'd be better off dead, no matter what you can't do.