How did the Smallpox Vaccine revolutionise the world of inoculations?

In
the late 18th century, smallpox was a major public health problem. It
was a highly contagious viral disease that killed millions.

There was no known cure for smallpox, In
1796, an English physician named Edward Jenner developed a new vaccine for
smallpox. Jenner noticed cowpox-exposed milkmaids
gained immunity against smallpox, he hypothesized that cowpox could be used
to protect people from smallpox. He tested his hypothesis by inoculating a
young boy named James Phipps with cowpox. Phipps developed a mild case of cowpox, but
he recovered fully. Two months later, Jenner inoculated Phipps
with smallpox, Phipps did not get smallpox, proving that
the vaccine was effective. Jenner’s smallpox vaccine was a major
breakthrough.

It was the first vaccine ever developed,
and it saved millions of lives.