Oral<unk> <unk>  (OPV) is one of the safest and most effective<unk> s that prevents millions of cases of<unk> , not only through direct immunization, but also through herd immunity. On rare occasions, the<unk>  is associated with paralytic<unk> . 
There are two subtypes of paralytic<unk>  that are related to OPV,<unk>  associated paralytic<unk>  and<unk>  derived paralytic<unk> .
Vaccine mediated polio infection
Vaccinia
Zika virus infection travel notice
Norovirus outbreak
Hantavirus infection
Zika virus infection
Poliomyelitis
Brucellosis Biological warfare