1 Oral polio vaccine is used internationally, but not in Canada since 1996
Oral polio vaccine viruses are shed in stool for weeks and are transmissible. When circulating among underimmunized populations, the virus can mutate and revert to a form that causes paralysis in underimmunized or immunocompromised people. Communities with low vaccine coverage are at risk of outbreaks. Inactivated polio vaccine is used in Canada and cannot cause disease.
2 Polio virus could be circulating in Canada
A 2022 report from New York State of vaccine-derived polio in an adult who was unvaccinated and immunocompetent documented the second community transmission of poliovirus known in the United States since 1979. (1) Several positive wastewater samples were detected from the state. The same virus strain was recently detected in wastewater in the United Kingdom. (2)
3 Underimmunized people (< 4 doses of a polio vaccine) are at risk of poliovirus infection
Poliovirus is an enterovirus that spreads through the...