Is it possible that retroviruses are alive and well inside the very vaccines that are supposed to protect us?

It is not known at this time whether or not these vaccines can cause cancer and alter your DNA because the studies have not been performed.

In 1954, national testing began on one million children, ages six to nine, who became known as the Polio Pioneers: half received the vaccine, and half received a placebo. One-third of the children, who lived in areas where vaccine was not available, were observed to evaluate the background level of polio in this age group. ref:http://www.salk.edu/about/jonas_salk.html