Nigeria has officially wiped out wild polio, but there have already been 15 cases of infection this year, caused by the live virus used in some vaccines
Source:
https://www.newscientist.com/article/2214302-wild-polio-has-been-eradicated-in-nigeria-but-infections-will-continue/?utm_campaign=RSS%7CNSNS&utm_source=NSNS&utm_medium=RSS&utm_content=home