The United States has joined a list of about 30 other countries with circulating vaccine-derived poliovirus (cVDPV) identified by the World Health Organization (WHO), the country's Centers for Disease Control and Prevention (CDC) said on Tuesday.

The CDC said this means that poliovirus continues to be transmitted in Rockland County and surrounding areas.

The polioviruses found in New York, both from the case of paralytic polio in an unvaccinated adult in Rockland County in New York and in several wastewater samples from communities near the patient's residence, meet the WHO's criteria for cVDPV.

The virus' genetic sequences from the patient from Rockland County and wastewater specimens collected in New York have been linked to wastewater samples in Jerusalem, Israel and London, indicating community transmission.

The cVDPV occurs when local immunity to poliovirus is low enough to allow prolonged transmission of the original weakened virus in the oral polio vaccine, according to the CDC.

As the virus circulates and more genetic changes occur, the virus can regain its ability to infect the central nervous system and cause paralysis.

"Polio vaccination is the safest and best way to fight this debilitating disease and it is imperative that people in these communities who are unvaccinated get up to date on polio vaccination right away," said Jose R. Romero, director of CDC's National Center for Immunization and Respiratory Diseases.

New York Governor issued an executive order declaring a state disaster emergency on Friday, which helps expand vaccination efforts and surveillance.