vaccinations

Viruses are behind many types of illness, from mild colds to severe diseases like acquired immunodeficiency syndrome (AIDS) caused by the human immunodeficiency virus (HIV). Even COVID-19 itself is mild for some and severe for others. Viruses have been found all over the Earth. Researchers estimate that they are ten times more common than bacteria. These tiny germs, that are not even a cell themselves, invade other organisms and are an unavoidable part of our lives.

Before the advent of vaccines, enormous epidemics of measles, mumps, whooping cough, polio, and other crippling diseases ravaged humanity around the globe. That frightening situation began to change when Edward Jenner, Louis Pasteur, and other pioneering medical researchers developed the first vaccines-which use a portion of a disease germ to stimulate the body's immune reaction to that malady. Today, hundreds of millions of people gain immunity to deadly diseases through vaccination.