Today’s Wonder of the Day was inspired by Tessa. Tessa Wonders, “Do people still get polio?” Thanks for WONDERing with us, Tessa!

Do you enjoy getting shots? What? No way! Who would answer "Yes!" to that question? Probably no one, right? That's how we imagine most kids would answer that question.

And it's understandable. Getting shots is not an enjoyable experience. Although it's usually not as scary or painful as we anticipate it might be, it's still not fun to be pierced with a sharp piece of metal.

Unfortunately, shots are a regular part of life for most kids as they grow up. Even if you're very healthy and never need a shot to help cure an illness, you still need a variety of vaccinations early in life to prevent a wide range of diseases.

Are all those vaccinations really necessary? Doctors think so, and you will, too, after you learn more about a terrible disease that's been mostly eliminated thanks to vaccines.

In the years following World War II, there was one disease that people feared more than any other: polio. In fact, historians believe the fear of contracting polio was only second to the fear of widespread nuclear war.

Polio (also known as poliomyelitis) is a contagious viral disease that's been around for thousands of years. However, its worst outbreak in the United States occurred in the first half of the 20th century.

In 1952, at the height of the polio outbreak, there were about 60,000 cases of polio in the United States, with approximately 3,000 deaths as a result of the disease. It's easy to understand why people were so scared.

Polio is an interesting disease in that it produces no symptoms in about 95% of cases. When it does produce symptoms in its worst form, known as paralytic polio, the polio virus enters the bloodstream and attacks the nervous system.

In particular, the polio virus would attack the nerves that control the muscles involved in breathing and movement, causing paralysis and respiratory trouble. One standard treatment for respiratory problems was to place polio patients in a large machine called an "iron lung," which would push and pull the chest muscles to make them work.

Although most people with less severe types of polio could make a full recovery with no long-term consequences, people with paralytic polio were often left handicapped and many died. Thanks to a man named Jonas Salk, however, polio soon became a thing of the past.

Dr. Salk developed a vaccine for polio in the early 1950s. He began testing the vaccine in 1952 in what would become one of the largest clinical trials in medical history. His vaccine was finally approved for general use in 1955, and it had an immediate and dramatic impact.

Cases of polio began to decline rapidly. In subsequent years, other versions of the polio vaccine were developed. Historians believe polio was effectively eliminated from the United States by 1979 and the entire Western Hemisphere by 1991.

Unfortunately, polio still exists in some parts of the world, including Africa and Asia. Health organizations around the world continue to administer polio vaccines in areas with polio outbreaks to try to eliminate the disease worldwide.

Wonder What's Next?

Join us in Wonderopolis tomorrow as we journey to France to visit a magical village!