Vaccine-derived poliovirus Type 2 in London’s environmental samples

The UK Heath Security Agency (UKHSA) has found poliovirus in sewage samples collected from the London Beckton Sewage Treatment Works. As part of routine surveillance, these detections occurred when an individual vaccinated overseas with the live oral polio vaccine (OPV) returned or traveled to the UK and briefly shed traces of a so-called vaccine-derived poliovirus (VDPV) in their feces, a rare genetically changed strain of the weakened poliovirus that was included in the oral polio vaccine (OPV). Investigations are underway after several closely related viruses were found in sewage samples taken between February and May. The VDPV has continued to evolve and is now classified as a vaccine-derived poliovirus type 2 (VDPV2), which on extremely rare occasions can cause serious illness, such as paralysis, in people who are not fully vaccinated. The detection of a VDPV2 suggests it is likely there has been some spread between closely linked individuals in North and East London...