Polio risk in America depends on vaccination coverage.

Polio still circulates in parts of the world, and an imported case four years ago in an under-vaccinated New York community paralyzed a 20-year-old; experts in the report say U.S. vaccination levels influence the risk.

Polio remains a subject of attention in the United States following a report that reviewed its history and recent events. The virus still circulates in parts of the world. The report notes that pockets of under-vaccinated people in the U.S. have been linked to local cases after international travel. Experts and public-health figures discussed how immunity levels affect the potential for outbreaks. Key points: - An international traveler brought the polio virus to an under-vaccinated New York community four years ago, and a 20-year-old unvaccinated man became paralyzed. - Polio can spread through water, food, and close contact, and there is no cure or FDA-approved antiviral treatment. - All 50 states require polio vaccination for school attendance, but more parents have used exemptions in recent years; Dr. Kirk Milhoan, head of the CDC advisory committee, suggested reevaluating the vaccine's role. Summary: The report indicates that polio's continued presence abroad and local pockets of lower vaccination coverage affect the risk of cases appearing in the United States. Undetermined at this time.