Britain’s polio-free status could be at risk for the first time in almost two decades after several samples of vaccine-derived poliovirus were found during routine London sewage testing.
Several closely related viruses were found in samples taken in north and east London between February and May. The findings suggest some spread between closely linked individuals and the virus has continued to evolve and is now classified as a vaccine-derived poliovirus type 2, the UK Health Security Agency said Wednesday.
