Gov. Chris Christie (R-NJ), Sen. Rand Paul (R-KY) and Hillary Clinton all chimed in on the recent vaccination controversy Monday. With major, potential presidential candidates lending their opinion it was sure to be a hot topic of conversation on Fox News' The O'Reilly Factor. Joining host Bill O'Reilly was his prime-time colleague Megyn Kelly who advocated for the measles vaccine, telling viewers "some things do require some involvement of Big Brother.” 

Kelly told O'Reilly that she believed in mandatory vaccinations and that the 10% of American parents who choose to not immunize their children were given "bad information years ago," but that the science is "very certain today" that vaccines are safe and effective.​ ​"Now there is good information​," she said. 

"This is going to be a big issue for politicians going forward, because it’s about Big Brother. But on the other hand, some things do require some involvement of Big Brother."

Kelly has three children and she stated emphatically that she “vaccinated all of them on time as the doctor prescribed.”