Polio has been found in the US Here’s what to know about the vaccine.

In July, a 20-year-old man from Rockland County, NY, was diagnosed with polio, a disabling and potentially deadly disease that had been considered eliminated in the United States. The infected man was unvaccinated and had not traveled overseas during the period when he could have been exposed to the virus, suggesting he contracted it in this country. Wastewater testing has since shown that the virus is present in nearby New York City, as well as Rockland and neighboring Orange counties. It was also found in the wastewater in London, prompting authorities to offer children ages 1 to 9 a vaccine booster. No cases have been reported there.