Ethan Lindenberger, an 18-year-old from Ohio, United States made headlines when he defied his mother’s wishes and got himself vaccinated in December. Now the high-school student has taken it upon himself to warn others about misinformation surrounding vaccination.

Lindenberger testified on Tuesday before the Senate Committee on Health, Education, Labor and Pensions and promoted vaccine education and outreach campaigns. He said much of his mother Jill Wheeler’s opposition to routine vaccinations came from the perception that they caused autism or brain damage.

This misinformation, according to him was spread by groups on social media, especially Facebook, which his mother consulted.

Wheeler, meanwhile, told the Associated Press that she was proud of her son for how he had handled himself but added that she did not agree with anything he said. “They’ve made him the poster child for the pharmaceutical industry,” she said.

Titled “Vaccines Save Lives: What Is Driving Preventable Disease Outbreaks?”, this was the second recent congressional hearing about vaccines, which are being held amid a resurgence of measles outbreak across the country.