It was the largest voluntary clinical field trial ever undertaken.

In an effort to test Jonas Saulk’s polio vaccine more than 60s years ago, a massive grassroots effort took place using 1.8 million children.

Called the “polio pioneers,” the childrem helped change the course of public help.

One shared his story with WGN.

For James Calabrese, the fear of COVID-19 is familiar.

“Back then, children were getting polio,” Calabrese said. “You would see them in wheelchairs and metal braces.”

At the time, Polio was widespread and causing paralysis in children.

“It seemed like an impossible time, like it seemed too steep a hill to climb,” Calabrese said. “But then we began to hear about things like a potential vaccine and suddenly then there was hope.”

His parents asked the 6-year-old if he’d like to participate in the clinical trial.

“How could you pass up a chance to stop a disease like that?” Calabrese said.

Children lined up at their schools where the trials were staged throughout the country.

“I was convinced when I took that serum that things were going to be okay for everybody,” Calabrese said. “I was sure.”

About a year and a half later, a letter arrived. In it, the government said Calabrese’s parents he was one of the 400,000 out of 700,000 kids who received the vaccine and not a placebo.

“It occurred to me that the kids who didn’t get the vaccine weren’t protected from polio,” Calabrese said. “And I wondered how they made out and I suppose that some of them didn’t make out so well.”

The government ended up giving Calabrese a certificate after he became a polio pioneer.