Not up for debate: the science behind vaccination

...My hopes were dashed as Wednesday night’s debate wound down, though. Questions about vaccines and autism were asked not only of Donald Trump, but also of the two physicians taking part: Ben Carson, a neurosurgeon, and Rand Paul, an ophthalmologist. The doctors, at least, should know better.

...There is simply no scientific evidence that links vaccines to autism. Many, many, many studies have confirmed this. The most recent Cochrane systematic review of research on the MMR vaccine included six self-controlled case series studies, two ecological studies, one case crossover trial, five time series trials, 17 case-control studies, 27 cohort studies and five randomized controlled trials. More than 15 million children took part in this research. No one could find evidence that vaccines are associated with autism.



....It’s also not correct to call autism an “epidemic,” as Mr. Trump often seems to do. Autism is more prevalent as a diagnosis than it used to be. But much of that in recent years is because we’ve changed the definition of what it means to have “autism spectrum disorder.” For instance, 10 years ago, two-thirds of children diagnosed with autism had below-average intelligence. But today only about a third of those diagnosed with A.S.D. do. The fastest-growing group of children with autism have average or above average intelligence. We’re being more inclusive in the diagnosis.



....Over time, researchers have been able to purify vaccines so that they contain fewer antigens, while still conferring immunity. They get the same results while asking less of the immune system. A single smallpox vaccine had more than 200 different antigenic proteins. In the 1980s, the seven vaccines routinely given to children contained thousands of antigens. Today, the number of antigens contained in all the vaccines given to a child by age 2 is less than 315. In contrast, it’s thought a child most likely fights off 2,000 to 6,000 antigens every day from the environment....


http://www.nytimes.com/2015/09/18/upshot/not-up-for-debate-the-science-behind-vaccination.html?_r=1