An investigation of the first U.S. polio case in nearly a decade found evidence of a connection between the U.S. infection and sewage samples from London and the Jerusalem area, according to a July 29 ProPublica report.
The results are preliminary and don't point to where the virus was first.
"That is still being investigated," Oliver Rosenbauer, the World Health Organization communications officer for the Global Polio Eradication Initiative, told ProPublica.
The Global Polio Eradication Initiative confirmed the report July 29, saying the case is type 2 circulating vaccine-derived poliovirus (cVDPV).
"While cVDPVs are rare, they have been increasing in recent years due to low immunization rates within communities," the Global Polio Eradication Initiative's website reads. "CVDPV type 2 are the most prevalent, with 959 cases occurring globally in 2020."
On July 21, health officials in Rockland County, N.Y. told state officials of a polio case detected in an unvaccinated man, and in the days following, the county launched polio vaccination sites.