It worries me when people say this, because it implies that you guys just regurgitate stuff without understanding it at all. There is no minimum vaccine threshold anywhere in the world for smallpox, it is eradicated, same with polio with the exceptions of a few isolated areas. The US is not unique in not vaccinating for smallpox, nobody but soldiers and researchers are still vaccinated for smallpox worldwide and most countries do not generally vaccinate for polio, because it doesn't exist in the wild in most countries. There are so many scary things that could happen because of people not vaccinating. The return of smallpox would require more than vaccine hesitancy though let alone the US "stopping vaccinating against it." The US has not routinely vaccinated for smallpox since 1972. This would require a lab leak or bioterrorism. Please, being ignorant in the correct direction is really not that much better than ignorance in the wrong direction. Learn more about issues.