The Centers for Disease Control and Prevention has sent a team to New York to investigate a polio case discovered in Rockland County.

The team will also assist in the administration of vaccinations throughout the county.

It’s unclear how long the CDC will stay in the county or whether the findings will be made public.

“The CDC continues to work with the New York State Department of Health to investigate a recent case of paralytic polio in an unvaccinated Rockland County resident,” the federal health agency said in a statement to ABC News. “These efforts include ongoing testing of wastewater samples for poliovirus and the deployment of a small team to New York to assist with the investigation and vaccination efforts on the ground.”

On July 21, the New York State Health Department announced that a patient in Rockland County had contracted vaccine-derived polio, the first case in nearly a decade in the United States.

This indicates that the unvaccinated patient was infected by someone who received the oral polio vaccine, which is no longer used in the United States.

Unlike the injection-based polio vaccine, which uses an inactive virus, the oral vaccine uses a live, weakened virus.

In rare cases, the virus spread through sewage can infect those who have not been immunized. This is distinct from wild polio, which infects people by naturally circulating in the environment.

The patient was later revealed to be a previously healthy 20-year-old man who had traveled to Europe. He was diagnosed after he went to the hospital when he developed paralysis in his legs.

Last week, the state health commissioner said “hundreds” of people in New York could be infected after the virus was found in wastewater samples in multiple counties.

According to health department data, 11 samples were genetically linked to the Rockland County patient as of Aug. 5, including six samples collected in June and July from Rockland County and five samples collected in July from nearby Orange County.

“Although no additional cases have been identified at this time, these findings suggest that more than one person in these communities is shedding the virus in their stool,” the CDC said in a statement. “These individuals may have no or only mild symptoms, such as a sore throat and fever, but they can unknowingly spread polio to those who have not been immunized.”

Dr. Mary Bassett, New York State Health Commissioner, has urged anyone who has not received the polio vaccine to do so.

According to state data, the statewide rate of polio vaccination is 78.96 percent, while the Rockland County rate is 60.34 percent. The rate in Orange County is even lower, at 58.66 percent.

“Based on previous polio outbreaks, New Yorkers should be aware that for every case of paralytic polio observed, hundreds of other people could be infected,” Bassett said in a statement Thursday. “When combined with the most recent wastewater findings, the Department views the single case of polio as the tip of the iceberg of a much larger potential spread.”

The statement continued, “We must meet this moment by ensuring that adults, including pregnant people, and young children by 2 months of age are up to date with their immunization — the safe protection against this debilitating virus that every New Yorker needs.”