New York health officials on Thursday called for people to get vaccinated against polio “right away” as they warned that the one confirmed case of the disease in the state could be “the tip of the iceberg” of a bigger outbreak. The alarm came after polio was detected in wastewater samples in several places and at different times in two counties north of New York City, which may indicate worrying community spread of the disease. “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,” Dr. Mary T. Bassett, the state’s health commissioner, said in a statement. “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.” Anyone who is unvaccinated against polio is at risk of contracting the incurable disease, which can cause paralysis and even be fatal.