Jenner used children to test a theory — based on folklore, not scientific evidence — that cowpox, a disease common in the rural parts of western England in the late eighteenth century, conferred immunity against subsequent exposure to smallpox. He tested his theory primarily on healthy children. He injected eight-year-old James Phillips first with cowpox then three months later with smallpox. The boy seemed unharmed and Jenner has been hailed as the discoverer of smallpox vaccine.
However, after Jenner vaccinated his own 18-month-old son, he suffered neurological brain damage; and both boys died of tuberculosis before the age of 21. In 1798, Jenner formulated a new vaccine after proclaiming that his first formulation had “no protective virtue.” But his new vaccine was met with public ridicule so he promoted his original formulation and convinced the Royal College of Physicians and the British Parliament in 1807, that his admittedly unprotective vaccine was “safe and effective” and could produce large revenues! Read Jenner On Trial and Vaccines — Injections of Death