Almost a million children aged one to nine across London are to be offered a polio vaccine to try to prevent the spread of the virus.
Health officials warned there has been “some transmission” of the virus in the capital after detecting poliovirus in sewage samples.
Polio, which was officially eradicated in the UK in 2003, can cause paralysis in rare cases and can be life-threatening.
While there have been no confirmed cases, officials sounded the alarm over the rising number of samples found in sewage in London.
The UK Health Security Agency (UKHSA), working with the Medicines and Healthcare products Regulatory Agency (MHRA), found poliovirus in sewage samples in London boroughs including Barnet, Brent, Camden, Enfield, Hackney, Haringey, Islington and Waltham Forest.
It was first detected at Beckton sewage treatment works earlier this year.
Officials said levels of the virus found in sewage and their “genetic diversity” suggests “some virus transmission in these boroughs”.
As a result officials are to launch a rapid vaccination programme among youngsters in London, where there are lower levels of uptake of the vaccine.
