"There are tens if not hundreds of thousands of cases that have been prevented over the years, because of all the vaccines that we use for all children in this country," said Lurie Children's Hospital Infectious Diseases Head Dr. Ravi Jhaveri.
But Robert F. Kennedy Jr., President-elect Donald Trump's nominee to be the nation's top health official, doesn't believe in vaccines.
"There is no vaccine that's safe and effective," Kennedy said.
That claim is false. Vaccines go through a robust approval process that takes several years.
Kennedy has endorsed a series of conspiracy theories that link childhood vaccines to autism, something Jhaveri says has been proven to be untrue.
"It's a theory that's been put forth and has been studied over and over again across multiple settings around the world, and that link has been disproven over and over," Jhaveri said.
SEE ALSO | Trump's cabinet, administration picks include close allies from his campaign. Here's a full list
If confirmed as secretary of Health and Human Services, Kennedy will oversee one of the largest departments in federal government, one that deals with food you eat and drugs you take. HHS includes the Food and Drug Administration and National Institutes of Health.
Illinois Sen. Dick Durbin calls the department a life-and-death agency. It is one, Durbin says, Kennedy is not qualified to lead.
"He is engaged in quack science and crazy theories right and left and draws a lot of attention because of it. I fear this man is going to bring those same ideas to the administration," Durbin said.
Public health experts, including former acting Director of the Center of Diseases Control Dr. Richard Besser, are calling the nomination of Kennedy "chilling."
"To see someone in that role, who has done more than just about anyone to undermine people's confidence in our vaccine system is absolutely, devastating," Besser said.
If Kennedy is confirmed, Lurie doctors say it will likely take some extra work over the next couple years to reeducate families on the safety of vaccines as disinformation will continue to spread.