The polio vaccines developed in the 1950s by Jonas Salk and Albert Sabin allegedly eradicated one of the most feared diseases of the 20th century. The media hailed the success of these vaccines as a modern day miracle. However, the polio story has a much darker side that has mostly been kept a secret.

Both Sabin’s live virus vaccine given orally and Salk’s inactivated virus vaccine given by injection were far from perfect. In fact, in 1955 the vaccine used in Berkley, California infected some 200 children, leaving several dead and many paralyzed. Yet this incident proved minor compared to what was later discovered.

In order to grow large quantities of the poliovirus, scientists needed to use Rhesus monkey kidney cells, which carried many different viruses. As a result, their polio vaccine became contaminated with a cancer-causing virus carried by these monkeys. This vaccine was given to almost 100 million people.

The virus found in this particular polio vaccine was SV40, or simian virus. It is present in human tumors, and research has established it to be a contributing factor in the rise of many types of cancer, including mesothelioma, bone, and brain cancer.

When the government became aware of this, it was downplayed for fear the public would stop accepting vaccination.