Urgent investigation into spread of vaccine-derived poliovirus

An urgent investigation is under way after scientists discovered that a vaccine-derived poliovirus is loose in London.

Several “closely related” viruses have been found in sewage samples from the capital taken this year, the UK Health Security Agency said.

So far, no cases of polio-related illness – such as paralysis – have been reported but the virus could be spreading in communities with low vaccination rates, the agency warned.

It believes the virus has been spreading between people with close links in north and east London.

Agency consultant epidemiologist Dr Vanessa Saliba said: “Vaccine-derived poliovirus is rare and the risk to the public overall is extremely low.

“Vaccine-derived poliovirus has the potential to spread, particularly in communities where vaccine uptake is lower. On rare occasions it can cause paralysis in people who are not fully vaccinated. Most of the UK population will be protected from vaccination in childhood, but in some communities with low vaccine coverage, individuals may remain at risk.

“We are urgently investigating to better understand the extent of this transmission and the NHS has been asked to swiftly report any suspected cases to the UKHSA, though no cases have been reported or confirmed so far.”