Why are vaccines so important?

Since vaccines were first developed in the late 18th century, they have been used to combat and even eradicate many deadly illnesses. And despite some concerns from skeptics, vaccines have been widely heralded by the scientific community and public health officials as one of the greatest medical breakthroughs of the modern era. But vaccines can only reach their full potential if enough people are inoculated to stop dangerous pathogens from spreading.

Vaccines work by using the weakened version of a pathogen to imitate — but not cause — an illness in a way that forces the body to develop a supply of defensive cells. These cells can then recognize and fight off a future infection should it occur. This process is different from other drugs because it prevents future illnesses rather than combating already-present infections.

Vaccines have eliminated some of the most dangerous, fatal diseases in human history. The World Health Organization in 1979 declared smallpox globally eradicated, and the Centers for Disease Control and Prevention (CDC) that same year proclaimed polio eradicated in the United States. Other vaccines have managed to push various diseases to the brink of extinction, such as tetanus and whooping cough.

Throughout the history of vaccines, several groups have risen as skeptics of the drugs’ safety and effectiveness. One ongoing movement, widely known as “anti-vaxxers,” claims that vaccines can cause autism and other illnesses — based on old, flawed studies that have been widely debunked.

A lot of research and the scientific community as a whole have definitively disputed these claims, finding that vaccines are generally safe despite a few minor side-effects like fever, allergic reactions, and fainting. And with no good alternatives, vaccines are the best way to fight horrifying diseases like polio and smallpox.

The big concern with anti-vaccine skepticism is that it may stop some people from getting vaccinated. That could prevent the population from achieving herd immunity, wherein so many people are vaccinated that disease-causing pathogens no longer have human sources to spread to and, as a result, can’t survive.