The aggravating thing is that this is a known problem with the oral vaccine. I read a paper from Stanford University about this. From 2015! This is not the one I saw but here is one....

https://med.stanford.edu/news/all-news/2015/04/emerging-form-of-poliovirus-threatens-hopes-for-eradication.html

Here's the heart of the issue.....

"These vaccine-derived viruses are escapees. They start in the intestines of a tiny fraction of people who receive the oral polio vaccine. The oral vaccine uses live, but attenuated, strains of poliovirus, meaning the pathogen has been altered to be harmless — or at least much less virulent. In about one in a million people, though, the attenuated poliovirus mutates in such a way that it regains its potency. Sometimes, it sickens the individual who got the vaccine, a problem known to doctors for decades."

"What’s come as a surprise, however, is that even if these mutated viruses fail to affect the person in whom they originate, they may escape into the environment in the individuals’ feces and start infecting people like wild viruses do."

So, why use the oral vaccine in Africa? We do not use it here. hmm........