Ethan Lindenberger, who was vaccinated for the first time at 18-years-old against his family's wishes, said misinformation should be the "primary concern" for people in the US.
Ethan Lindenberger spent his first 18 years unvaccinated - defenceless against tetanus, polio, measles. But in December, defying his mother, he went and got inoculated, a rebellion that earned him an invitation to the US Congress.
"I grew up understanding my mother believed vaccines are dangerous, as she would speak openly about her views both online and in person," the high schooler said on Tuesday, in testimony before a Senate hearing on contagious disease outbreaks.
But Mr Lindenberger, still 18, said he did his own research, became convinced that information in defence of vaccines "outweighed the concerns heavily" of the so-called anti-vax movement, and started receiving the shots he had missed out on as a child.
In recent weeks he has become a hero of believers in modern medicine in the US, where experts and elected officials still struggle to convince some that their refusal to get themselves or their children vaccinated is fueling several recent outbreaks of measles.
Similar dangerous outbreaks have occurred in Brazil, France and Ukraine.
Many vaccines are theoretically mandatory for students to attend school in the US.
But almost all states - 47 out of 50 - allow exemptions on religious, moral, or personal grounds, including Mr Lindenberger's state of Ohio.
"It was a slow progression to start to see evidence" of the effectiveness and safety of vaccines, he said, adding that he grew intrigued by so many people who "disagreed with my mum" and sought to dismiss her claims online.
But he sought out information from the US Centers for Disease Control and Prevention, public health organisations and scientific journals.
When he showed his mother the articles explaining, for example, that the measles, mumps and rubella (MMR) vaccine did not cause autism, he said she replied: "That's what they want you to think".
Mr Lindenberger's defiance of parental guidance earned him the attention of thousands, including members of the US media and Congress.
He was soon invited to appear before a panel of senators, several of whom praised his persistence in seeking out the truth.
Mr Lindenberger said one of the main challenges now is to counter the online anti-vaccination sites that peddle conspiracy theories.
"The sources which spread misinformation should be the primary concern of the American people," he said.