Poliovirus has been detected in sewage samples collected from the London wastewater system in recent months. The UK Health Security Agency (UKHSA) said a total of 116 virus isolates were identified in 19 sewage samples collected in London between February and July.
Since 2003 the UK has been declared polio-free, however, a new string of detections has sparked an investigation “to protect the public”.
The UKHSA is also urging Britons to “make sure polio vaccines are up to date, especially parents of young children who may have missed an immunisation opportunity.”
Polio was largely eradicated thanks to the vaccination effort, with the last case of wild polio contracted in the UK in 1984.
Most adults and children who are vaccinated against polio will not become sick from the virus, and many people do not even realise they are carrying it.
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Although polio mainly affects children under the age of five, the World Health Organization warns it can impact people of any age, especially those who have not been vaccinated.
The UK is considered by the World Health Organization to be polio-free, with low-risk for polio transmission due to the high level of vaccine coverage across the population.
However, vaccine coverage for childhood vaccines has decreased nationally and especially in parts of London over the past few years, so UKHSA is urging people to check they are up to date with their vaccines.
Jane Clegg, chief nurse for the NHS in London said: “The majority of Londoners are fully protected against Polio and won’t need to take any further action, but the NHS will begin reaching out to parents of children aged under five in London who are not up to date with their Polio vaccinations to invite them to get protected.
How have polio traces gotten into UK wastewater?
As part of routine surveillance, “vaccine-like” polioviruses are occasionally detected each year in UK sewage samples.
The UKHSA says these have always been one-off findings that were not detected again.
The UKHSA continued: “These previous detections occurred when an individual vaccinated overseas with the live oral polio vaccine (OPV) returned or travelled to the UK and briefly ‘shed’ traces of the vaccine-like poliovirus in their faeces.
“Investigations are underway after several closely-related viruses were found in sewage samples taken between February and May.
“The virus has continued to evolve and is now classified as a ‘vaccine-derived’ poliovirus type two (VDPV2), which on rare occasions can cause serious illness, such as paralysis, in people who are not fully vaccinated.”