A polio virus particle, as shown in a 2014 illustration made...

A polio virus particle, as shown in a 2014 illustration made available by the Centers for Disease Control and Prevention. Credit: AP

Although wastewater testing following an outbreak of polio earlier this year has found less of the virus detected in counties of concern, including Nassau and areas of New York CIty, polio vaccination rates remain "too low," the state Department of Health said.

So, officials will continue to urge vaccination for those 18 and younger.

The announcement coincides with the expiration last week of an executive order declaring a statewide disaster emergency due to "the ongoing spread of polio" in New York.

That order was issued after a case of paralytic polio was identified on July 21 in an unvaccinated resident of Rockland County who state officials said had no international travel during the incubation period for polio. It originally was to expire in November but was extended to Dec. 8.

Polio was declared eliminated in the U.S. in 1979 and the Rockland case was determined to be a case of vaccine-derived poliovirus, the first in New York since 1990.

Vaccine-derived poliovirus is a strain related to the weakened live poliovirus found in the oral vaccine, according to the Centers for Disease Control and Prevention.

"If allowed to circulate in under- or unimmunized populations for long enough, or replicate in an immunodeficient individual, the weakened virus can revert to a form that causes illness and paralysis," the CDC says.

The health department said that since July more than 46,718 polio vaccine doses have been administered to those 18 and younger in Rockland, Orange, Sullivan and Nassau counties, and 86% of those immunizations were administered as combination vaccines in Rockland and Orange.

But officials said the statewide polio vaccination rate in 2-year-old children remains at about 79% and that in several counties, and areas of certain counties, it remains "significantly less" — causing officials to continue pushing for vaccinations focused on high-risk populations through education and outreach.

Wasterwater sampling 'ongoing'

Officials said genetically-related poliovirus have been detected in wastewater samples collected in Nassau, Kings, Queens, Orange, Rockland and Sullivan counties between April and October.

Of 94 positive samples, 87 were found linked to the Rockland case, the state health department said. Forty-four of those samples were collected in Rockland, 28 in Orange, 13 in Sullivan, one in Brooklyn and a portion of Queens, and one in Nassau.

The Nassau sample was collected in August, the health department said.

The seven remaining positive samples have not been genetically linked, and none of those were found in Nassau. Wastewater in Suffolk has not been tied to any positive test findings.

State officials said that wastewater surveillance is part of "an active, ongoing effort" in partnership with local, national and global public health authorities. Officials claim the source data is "entirely anonymous."

"From the start, the state Department of Health — together with our partners at national and local levels — launched a focused, urgent response to protect New Yorkers against polio," state Health Commissioner Dr. Mary T. Bassett said in a statement, adding: "That work — including enhanced clinical surveillance, nation-leading wastewater surveillance, and driving vaccinations in affected areas — is ongoing and will continue . . . We are unwavering in our commitment to keep up efforts to build out long-term vaccination strategies."

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