Dutch lens grinder Zacharius Jannssen invents the microscope.
The first microscope
Around this time Hooke published the first drwing of cork cells.
Anton van Leeuwenhoek Discovers Organisims
Around this time Anton dicovered the existence of microorganisims
Edward Jenner develops a method to protect people from smallpox by exposing them to the cowpox virus.
In his experiment, he uses the pus from a dairymaid's cowpox postule into scratches on the arm of his gardener's 8-year-old son, and then exposes him to smallpox six weeks later (which he does not develop). The process becomes known as vaccination from the Latin vacca for cow. Jenner is sometimes called the founding father of immunology.
Ignaz Semmelweis stops Childbed Fever
Around this time Ignaz discovers that if you wash your hands before giving birth to a child it will most likely not get puperal fever.
Louis Pasteur Disproved Spontanues Generation
Around this time Louis disproved that spontaneaus generation is not true when he did an expirriment with raw meat and flies.
Microbes can cause Infectious Disease
Germs can cause infectious disease. Which can be spread by the spreading of microbes.
Around this time he discovered that microbes can be stopped from spreading with chemicals.
Louis Pasteur and Robert Koch establish the germ theory of disease.
According to germ theory, a specific disease is caused by a specific organism. Before this discovery, most doctors believe diseases are caused by spontaneous generation. In fact, doctors would perform autopsies on people who died of infectious diseases and then care for living patients without washing their hands, not realizing that they were therefore transmitting the disease.