More than 95 million Americans are now fully vaccinated against COVID-19, but there are still many who remain on the fence. Vaccine hesitancy in the U.S. isn’t new -- it’s something that Americans have seen many times before. Decades ago, the polio virus was one of the most feared diseases in the United States. The development of a polio vaccine was widely celebrated, but one early batch of the vaccine was manufactured incorrectly, leading to some cases of paralysis and death. When the vaccination program resumed, many were hesitant to get the shot -- especially teenagers. Health officials needed help to encourage the public to get vaccinated, and so they looked to a rising star. In the video above, you can see pictures of Elvis Presley, at just 21 years old, smiling widely as he was vaccinated for polio. In October of 1956, Elvis got the polio vaccine backstage just before his performance on the Ed Sullivan Show. His target audience was the teenagers and young adults who thought they weren’t at risk for the deadly disease. The photos of Elvis’ vaccination were circulated in newspapers around the nation the next day. Officials say the percentage of teenagers that ultimately received their polio vaccine rose from 6 percent to almost 80 percent in six months after Elvis’ promotion. Now, that increase wasn’t solely thanks to Elvis, but his impact was significant enough to be dubbed the “Elvis effect.” The rising rock star was heavily involved with the March of Dimes, so he reportedly didn’t think twice about getting the polio vaccine. Is there a celebrity who could have the same impact now? Plenty of stars have been vaccinated for COVID-19 so far. Dolly Parton drew widespread praise for not only helping to fund Moderna’s coronavirus vaccine, but for also receiving her vaccination publicly. All of the living former presidents and their spouses have been vaccinated against the virus. Also on the list of public figures who have been vaccinated are the Pope, the Dalai Lama and the Queen -- and a long list of celebrities, such as Tyler Perry, Kareem Abdul-Jabbar, Nick Jonas and Ryan Reynolds. But health experts aren’t expecting an “Elvis effect” this time around; they think hesitant people are far more likely to get vaccinated if they hear the message from their own doctor, pastor or another trusted member of their own community. Experts believe that there are big stars like Beyoncé or LeBron James who could still have an impact on vaccination rates, especially among young people.