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In a simple photo, Mark Zuckerberg sparked a conversation about vaccines.
The 31-year-old Facebook CEO shared a photo Friday of himself and his five-week-old daughter, Max, in a doctor's office.
"Doctor's visit -- time for vaccines!" the 31-year old Facebook CEO wrote in the post.
In the picture, Zuckerberg is holding Max, who is wearing an adorable winter onesie, on his lap.
The post has already has more than 2.5 million likes and over 24,000 shares. It's also received a long thread of comments.
Many Facebook users are thanking Zuckerberg for his simple pro-vaccine statement.
Stuart Duncan wrote: "As someone with autism, with a son with autism, as someone who is constantly watching good people put their own children at serious risk because of old, fraudulent fears of vaccines and autism...thank you for being sensible."
Anti-vaccinators, who believe that vaccines received during infancy can cause serious health problems, are also chiming in on the post.
"Vaccines are largely ineffective and even if they don't result in Sudden Infant Death Syndrome or Autism Spectrum Disorder, as they did for 9 year old Hannah Poling: they are extremely unhealthy," wrote Colleen Kenny.
While some parents fear vaccines, the science around them is very clear. Studies have shown that modern vaccines are very safe and scientists overwhelmingly say vaccines do not cause autism.
Even before the birth of Max, Zuckerberg's first child with wife Priscilla Chan, the CEO said he was a supporter of doctor-recommended vaccines.
Last February, for his 2015 book club, A Year Of Books, he chose the book "On Immunity" by Eula Bissas the club's fourth book.
As Zuckerberg wrote in a related Facebook post, "this book explores the reasons why some people question vaccines, and then logically explains why the doubts are unfounded and vaccines are in fact effective and safe."
The book club was part of Zuckerberg's 2015 New Year's resolution. His 2016 resolution? To build an artificial intelligence that resembles the one called J.A.R.V.I.S (Just A Rather Very Intelligent System) in the "Iron Man" films.