When we think of heroes, we think of people who serve others for the greater good, even in the face of challenging odds. Whether it's a police officer, firefighter, or even a comic book superhero, we know that they go to work every day and try to protect others from harm.
While they aren't fighting robbers or villains, there is one group of heroes working tirelessly to save humans from one of the biggest threats of all time: germs. Yes, little microscopic bacteria, viruses, and fungi have killed more people than anything else in history.
Over the years, curious and driven scientists have pushed the limits of human knowledge, trying to learn how to fight back against this threat and preserve human health. This has led to discovering the existence of microbes, how they attack the body, how to heal an infection, and even how to prevent infections from happening in the first place.
While infectious disease once killed half of all children under the age of 5, infant mortality has never been lower and adults are enjoying longer and healthier lives.
As SciShow's Michael Aranda explains, the greatest medical discoveries were the result of years of study and collaboration, with countless people contributing to the heroic medicines that are now commonplace.
That said, there are three people in particular who have saved billions of lives by making germs less of a threat, and most people don't even know their names.
Check out the video below and learn why we all owe so much to Louis Pasteur, Joseph Lister, and Maurice Hilleman.