Washington, Dec 1 : The US Centers for Disease Control and Prevention (CDC) announced that it will expand wastewater testing for poliovirus in select areas across the country. Michigan and Philadelphia are among the first locations to start collecting wastewater samples in specific communities for analysis at the CDC's polio laboratory, Xinhua news agency reported. The findings from wastewater testing will help jurisdictions prioritise vaccination efforts in identified communities of concern, said the CDC. "Wastewater testing can be an important tool to help us understand if poliovirus may be circulating in communities in certain circumstances," said Jose R. Romero, director of the CDC's National Center for Immunization and Respiratory Diseases. Vaccination remains the best way to prevent paralytic polio, Romero said. In the US, the risk of poliovirus to the public is low because most people, greater than 92 per cent of Americans, were vaccinated during childhood, according to the CDC. /IANS