Dr. Anthony Fauci, the United States' top infectious disease expert, on Saturday told CNN's Jim Acosta that he's "certain" smallpox and polio would still be present in the United States if their vaccine drives faced misinformation campaigns  similar to the ones currently plaguing COVID-19 inoculation efforts. 

"If you look at the extraordinary, historic success in eradicating smallpox and eliminating polio from most of the world — and we're on the brink of eradicating polio — if we had had the pushback for vaccines the way we're seeing for certain media, I don't think it would have been possible at all to" eradicate the two deadly diseases, Fauci said. 

There's no singular reason why people in the United States remain hesitant about or outright opposed to getting a COVID-19 shot, but Fauci and others, including President Biden, believe that misinformation coming through television screens and social media feeds has played a significant role in shaping people's views and, subsequently, slowed down the rollout as infections pick back up due to a combination of loosening restrictions and the spread of the more transmissible delta variant.