Jonas Salk

Although no one was safe from polio, the virus mostly affected kids. Most who were infected showed no symptoms, though they were still highly contagious. Others experienced sore throats, pain, and stiffness.

But for some, the effects of polio were more severe. Their muscles would become paralyzed, so they couldn’t walk or breathe on their own. Many had to be put inside an iron lung, a metal tank-like machine that helped them breathe.

And the disease spread very easily, through human waste in the water supply or through an infected person’s coughs and sneezes. So sick kids were quarantined to stop the virus from spreading.

Salk always knew that he wanted to make a difference in the world. He had already been studying medicine for years when the polio outbreak swept the nation. In 1947, he began to work on a polio vaccine, a shot that contained harmless parts of the virus.

“A vaccine takes a part of the virus and shows it to your immune system,” explains Nicole Doria-Rose, a scientist at the National Institutes of Health. “Your immune system remembers the virus and is prepared to fight it off right away if you’re exposed to it.”

By 1954, Salk had created what he thought to be a successful polio vaccine. It was a remarkable discovery—but would it work? Before making it available to the public, Salk had to be sure it was safe. So he tested it on his wife, his sons, and even on himself. It was then tested on nearly 2 million kids.

Finally, on April 12, 1955, doctors made an important announcement that would change the world. Salk’s polio vaccine had been proven safe, effective, and ready for use.

The American people were relieved. They no longer needed to live in fear.

Salk’s discovery saved countless lives and paved the way for many vaccines that followed. Today, vaccines are being tested to help in the fight against Covid-19. Doria-Rose says that Salk and scientists like him have changed the world with life-saving vaccines.

“They have had the greatest impact of any medical invention ever, in terms of the number of lives saved,” she says.

1. Why were kids with polio quarantined in the late 1940s and early 1950s?

2. How is a vaccine supposed to work, based on the article?

3. Why was April 12, 1955, an important day in America?