• New York state Health Commissioner Mary Bassett warned that the confirmed polio case in an unvaccinated adult and the detection of the virus in sewage could indicate a larger outbreak is underway.
• "Based on earlier polio outbreaks, New Yorkers should know that for every one case of paralytic polio observed, there may be hundreds of other people infected," Bassett said.
• State health officials are urgently calling for people who are unvaccinated to receive their shots as soon as possible.

Hundreds could have polio after an adult in the New York City metro area caught the virus and suffered paralysis last month, the state's top health official said this week.

New York state Health Commissioner Mary Bassett warned that the confirmed polio case in an unvaccinated adult, coupled with the detection of the virus in sewage outside the nation's largest city, could indicate a bigger outbreak is underway.

"Based on earlier polio outbreaks, New Yorkers should know that for every one case of paralytic polio observed, there may be hundreds of other people infected," Bassett said. "Coupled with the latest wastewater findings, the department is treating the single case of polio as just the tip of the iceberg of much greater potential spread."

Bassett said it is crucial that children are vaccinated by the time they are 2 months old, and all adults — including pregnant women —who have not received their shots should do so immediately.

"As we learn more, what we do know is clear: The danger of polio is present in New York today," Bassett said.

New York state health officials confirmed last month that an unvaccinated adult in Rockland County had caught polio and was hospitalized with paralysis. Health officials subsequently found three positive polio samples in Rockland County wastewater and four positive samples in the sewage of adjacent Orange County.

The sewage samples that tested positive for polio are genetically linked to the strain which the unvaccinated adult caught. The findings do not indicate that the individual who caught polio was the source of transmission, but local spread could be underway, health officials said.

"These findings provide further evidence of local — not international — transmission of a polio virus that can cause paralysis and potential community spread, underscoring the urgency of every New York adult and child getting immunized," the New York State Department of Health said.

Rockland County has a polio vaccination rate of 60%, while Orange County has a vaccination rate of 58%, according to health officials. The statewide vaccination rate for polio is nearly 79%.

The U.S. was declared polio free in 1979 and a case had not originated in the country since then, but travelers have occasionally brought the virus into the U.S., according to the Centers for Disease Control and Prevention. New York last confirmed a polio case in 1990 and the U.S. previously confirmed a case in 2013, according to state health officials.

Children should receive four doses of the polio vaccine. The first dose should be administered by 2 months of age, the second dose at 4 months, the third at 18 months and the fourth by age 6, according to state health officials. Unvaccinated adults should receive three doses.

Polio is a highly infectious, devastating virus that can cause paralysis. The virus struck fear into parents' hearts in the 1940s before vaccines were available. More than 35,000 people became paralyzed every year from polio during that period. But a successful vaccination campaign in the 1950s and 1960s dramatically reduced the number of cases.