Health experts have been urging immunizations among the unvaccinated, as some states have rates below 90 percent.
Below is a timeline of the initial wastewater sample collections to its present ongoing investigation of the case.
April: Wastewater sample collected in New York contains polio, but researchers are unable to genetically link it to other samples.
June: More wastewater samples detect polio in the state.
July 21: New York confirms the first polio case in an unvaccinated Rockland County man.
Aug. 1: An investigation into the case finds evidence of a connection between the U.S. infection and sewage samples from London and the Jerusalem area.
Aug. 5: Mary Bassett, MD, the state’s top health official, warns the single case may be the “tip of the iceberg.”
Aug. 9: The CDC deploys a team to New York to assist the state’s health department with its investigation of the case.
Aug. 11: The CDC weighs offering some New Yorkers an extra dose of the polio vaccine amid concerns of a silent community spread. “We’re looking into all aspects of how to deal with this. At this point, we don’t have a definitive answer,” José Romero, MD, director of the CDC’s National Center for Immunization and Respiratory Diseases, tells CNN.
Aug. 15: Health officials detect the virus in wastewater in New York City, suggesting “likely” local circulation of the virus.
Aug. 17: A CDC report finds changes to the genetic makeup of the virus suggest it may have been spreading somewhere in the world for a year.
Aug. 17: NYC Health+Hospitals announces it will expand its wastewater surveillance program to test for polio and monkeypox along with COVID-19 and the flu.
Aug. 19: USA Today reports health experts do not expect a national outbreak of polio similar to COVID-19 or monkeypox.
Aug. 29: The CDC detects the virus in four wastewater samples from Sullivan County in New York.
