The big question is whether the wider public is at risk.
Dr Saliba said: “Vaccine-derived poliovirus is rare and the risk to the public overall is extremely low.
“Most of the UK population will be protected from vaccination in childhood.”
Dr Saliba added: “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.”