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Why do some people oppose vaccination?

Some groups oppose vaccination — or at least the current vaccination schedule for children — out of concerns that vaccines can lead to long-term health problems, particularly autism.

Actress Jenny McCarthy became an especially well-known face of the anti-vaccination movement — widely known as “anti-vaxxers” — after her son was diagnosed with autism. McCarthy, who leads Generation Rescue, claims the rise of autism diagnoses coincides with a more aggressive vaccination schedule for children in the United States.

To be clear, the current scientific evidence shows no link between vaccines and autism.

Although it’s easy to characterize people like McCarthy as anti-science, they genuinely do believe that the evidence is on their side. They point to, for example, a 1998 study — which has now been widely debunked — that claimed to have found a link between vaccines and autism. But the evidence they cite tends to be cherry-picked, and ignores the overwhelming scientific consensus, which has developed over decades of research, that vaccines are safe and effective.

Anti-vaccination movements aren’t new. They actually date back to the late 18th century, with the advent of the smallpox vaccine. Some Christian clergy said the vaccine violated religious principles because it used parts from an animal. Others voiced a lingering distrust for medicine. Still others objected to a government-mandated vaccination as a violation of personal liberties.

British satirist James Gillray in 1802 captured the sentiment in a cartoon that implied people could become part cow if they took the smallpox vaccine.

vaccine cartoon

The smallpox vaccine never led to such outcomes. Instead, the World Health Organization in 1979 said smallpox had been eradicated worldwide, largely because of widespread inoculation.

But smallpox was only eradicated because enough people were inoculated that the virus could no longer find a human host to spread to and develop in. If it wasn’t for the high coverage rate of the smallpox vaccine, the disease would likely remain with us today.

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