The man who started this assertion was actually paid by lawyers.
Measles was once declared eradicated in the United States due to a highly effective vaccination program. However, when the assertion of "vaccines cause autism" became prevalent, significantly less number of parents were vaccinating their children against measles, causing the disease to re-emerge and eventually causing deaths due to unvaccinated U.S. residents traveling internationally. Measles is now one of the leading vaccine-preventable diseases caused by death.
So, how did we go from not a single case of measles in the United States for at least twelve consecutive months to hundreds of cases a year?
It all started from a 1998 peer-reviewed medical article written by a British surgeon, Andrew Wakefield, and it consisted of a study that he did with only twelve children, most of which he selected himself. A true medical study includes at least hundreds of people who volunteered to be part of the study, and the people in it needs to be randomized to represent a wide variety of races and genders. Instead of conducting the study out of true intentions for the betterment of the world, Wakefield was being paid by lawyers who were suing over alleged vaccine injuries. Not only that, the children in his study were the children of the parents suing, and he treated them unethically. This raised concerns that led to the lost Wakefield's medical license, and ultimately, the retraction of his study from the British Medical Journal.
Unfortunately, his assertion of "vaccines cause autism" is still prevalent to this very day.
More and more people suffer from measles over the years. In 2004, there were only 37 cases of measles in the U.S., but by 2014, that number raised to 667. In the following year, in January of 2015, an outbreak in Disneyland caused 111 cases, which were 59% of the cases that year. The U.S. ended up with a total of 188 cases by the end of 2015. Although these numbers decreased from the year 2014 to 2015, the U.S reported 375 cases in 2018, the second largest number of cases of measles since it was eradicated in 2000, with 667 cases in 2014 being the first. And to think, there was not a single case of measles in the U.S. for at least twelve consecutive months back when it was eradicated, but since then, the U.S. has seen nearly 3,000 cases since 2001.
Measles could still have been eradicated in the U.S by now if it weren't for parents choosing not to vaccinate their children against the disease, and instead, choosing to believe in Wakefield's assertion of "vaccines cause autism". The link between vaccines and the eradication of a disease doesn't only pertain to the measles vaccine and the disease itself. You don't hear on the news about many of the diseases that we have been vaccinated against since we were children. "Thanks to widespread vaccination, the United States has been polio-free since 1979," and smallpox has been eliminated in the U.S. since the 1950s.
But the elimination of a disease doesn't have to stop there. Any disease can be eliminated if there is a vaccine available for it. The most obvious example would be COVID-19. If enough people, not only in the U.S. but also worldwide, were to get the COVID-19 vaccine, cases would be significantly less than what it is now, and we would see a continued decline in cases throughout the following months and years. However, vaccine hesitancy is still prevalent, with the assertion of "vaccines cause autism" still being one of the many concerns even though it's not a valid concern.