Polio vaccination rates in some areas of the US hover dangerously close to the threshold required for herd immunity – here's why that matters

Given recent headlines, you may be wondering why polio is even an issue in 2022. For more than 60 years, vaccines against the poliovirus have protected virtually everyone in the United States from the disease. Due to an enormously successful polio vaccination campaign beginning in the 1950s when the first polio vaccines became available, by 1979 polio was considered eliminated in the U.S.

Unfortunately, even today, there are communities in the U.S. that have lower-than-necessary polio vaccination rates. Because many people have not been vaccinated, there is now a real possibility of a resurgence of polio in the U.S.

As a clinical professor of pharmacy, I train future pharmacists about how vaccines work, their importance and how they prevent diseases.

Public health experts’ longstanding concerns over falling vaccination rates rose to the surface when, in July 2022, a man from Rockland County, New York, was diagnosed with polio, the first such diagnosis in the U.S. in nearly a decade. The patient – who developed the severe, paralytic form of the disease – had been exposed to an altered live vaccine strain from overseas.

Then on Sept. 9, 2022, New York declared a state of emergency due to ongoing poliovirus transmission. As of that date, using wastewater surveillance, officials had identified 57 samples of poliovirus in wastewater from four New York counties. More than half of those were detected in the same county where the adult patient is from, just outside New York City.

As a result of the continued poliovirus detection in wastewater, the Centers for Disease Control and Prevention declared that the U.S. now meets the World Health Organization’s criteria for “a country with circulating vaccine-derived poliovirus.”