WASHINGTON (AFP) - Ethan Lindenberger spent his first 18 years unvaccinated - defenceless against tetanus, polio, measles. But in December, defying his mother, he got inoculated, a rebellion that earned him an invitation to 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 (March 5) in testimony before a Senate hearing on contagious disease outbreaks.
But Lindenberger, still 18, said he did his own research and became convinced that information in defence of vaccines outweighed the concerns of the so-called anti-vax movement.
In recent weeks he has become a hero of believers in modern medicine in the United States, where health officials struggle to convince some that their refusal to get themselves or their children vaccinated is fueling a resurgence of measles.
Pressure to boost vaccinations has surged amid the worst measles outbreaks in years in several US states including Washington, where the governor has declared a state of emergency.
Similar dangerous outbreaks have occurred in Brazil, France and Ukraine.
Lindenberger, testifying alongside distinguished health experts and officials, said "it was a slow progression to start to see evidence" of the effectiveness and safety of vaccines.
But he grew intrigued by so many people who "disagreed with my mom" and sought to dismiss her claims online.
He began studying reports by the US Centres for Disease Control and Prevention, visiting public health organisation websites, and poring over 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."
Many vaccines are theoretically mandatory for children to attend school in the United States.
But almost all states - 47 out of 50 - allow exemptions on religious, moral, or personal grounds, including Lindenberger's state of Ohio.
What got Ethan's vaccination quest noticed was his November post on the discussion website Reddit: "My parents are kind of stupid and don't believe in vaccines. Now that I'm 18, where do I go to get vaccinated?"
He received thousands of responses, and the US media came calling.
He soon got vaccinated against hepatitis A and B, influenza, tetanus and papillomavirus. He says he has also received MMR and polio vaccines.
DISINFORMATION ON FACEBOOK
Seated before some of America's most senior lawmakers, he was praised for his persistence in seeking out the truth.
"I applaud your critical thinking skills," said Democratic Senator Tim Kaine.
"I'd love to be a guest at your Thanksgiving dinner at your house," quipped Senator Lamar Alexander, a Republican.
Ethan's mother did not testify.
"I just continue to try and be respectful and as kind as I can and share the truth with her," Lindenberger told AFP.
"I think she understands that it's important to me."
Ethan, who lives with his father and wants to become a pastor, firmly believes his mother had good intentions in refusing to vaccinate her children.
He said a main challenge now is to counter the online anti-vaccination sites that peddle conspiracy theories by using "anecdotal" information that can ring true for concerned parents.
"People don't resonate well with information and data," Lindenberger said. "My mom reaffirmed that her position was correct because she knows people and she sees stories - but correlation doesn't equal causation."
Lindenberger says such personalised accounts should be answered by equally personal stories about the deaths and other harm caused by infectious diseases that vaccines were created to eradicate.
"When you convince parents that... their children are at risk, that's a much more substantial way to cause people to change their minds."
Ethan has four younger brothers and sisters. Do they agree with him?
"So far, there's been a substantial leaning towards my side," he said.
Some people attending the hearing, including anti-vaccine activists, were not convinced by Ethan's arguments.
One of them, Jena Dalpez from Washington state, which has recorded more than 70 measles cases since January, argued that parents of unvaccinated and infected children "knew the risks."