The country has not seen a case of the disease in three years.

Most people don't have anything to worry about. Marny Eulberg said that unless you're unvaccinated, it's not worth it.

The New York State Department of Health said an unvaccinated person from Rockland County probably contracted the disease from someone who had taken an oral vaccine.

Eulberg said that this instance will be attributed to the oral vaccine, which contains weakened live strains of the virus.

The weaker strain of the vaccine can evolve into a natural version of the virus that can be passed on to unvaccinated people. This is a vaccine case. This wouldn't have happened if the person in New York had beenvaccinated.

The majority of people in the United States have been protected against the disease by the age of two years old, according to the Centers for Disease Control and Prevention. Some people are granted religious exemptions and some states don't.

She said that Pio is an infectious disease that attacks the nerves in the spine that tell the body what to do.

New York's Rockland County is making it easy for local residents to get the vaccine by announcing clinics.

Five years before a vaccine was available in the U.S., Eulberg was bitten by the disease. She was in the hospital for a long time. She had to use a leg brace and crutches to get around as a child.

She did not need a brace or crutches until she was in high school. Her condition deteriorated after 35 years.

She said that half of the people who have survived the disease experience some level of paralysis. The most likely explanation is that the surviving nerves wear down over time.

Eulberg said that it's not going to come back. It can happen to up to 50% of the people who have had the disease in the past.

Poor countries that struggle with vaccine rates and clean water are still home to the world's last case of the disease. According to the CDC, most cases are in Afghanistan and Pakistan.

The Bill and Melinda Gates Foundation and the Rotary International renewed their partnership in January of this year.

The Gates Foundation is one of NPR's funders.