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The virus that causes polio has turned up in sewage samples in London. It would be a disturbing number of samples. However, the disease – which was especially common in the 1950s – has been eradicated from the United Kingdom since 2003.
ltoBron: The Guardian, BBC
The UK Health Security Agency (UKHSA) says the virus was likely imported into London. Scientists believe that someone abroad has been vaccinated with the live oral polio vaccine, which has not been used in the United Kingdom since 2004.
In rare cases, that form of the virus can then be passed on to others and mutate into what is known as “vaccine-derived” polio. Although this virus is weaker than the original or “wild” form of the disease, it can still cause serious illness, including paralysis, in unvaccinated people.
A cluster for the first time
According to the agency, the risk is low, but parents should ensure that their children are fully vaccinated against the disease. “The majority of the UK population will be protected by vaccination in childhood, but in some communities with low vaccination coverage, individuals may continue to be at risk,” said Dr. Vanessa Saliba, consultant epidemiologist at UKHSA.
The polio vaccine is given three times to children before they are one year old, and then again at the age of three and fourteen. The vaccination coverage of the first three doses in London is around 86%, which is well below target, while the rest of the UK is over 92%.
A small number of polio virus samples are discovered each year in sewage monitoring, but this is the first time a cluster of genetically related samples has been repeatedly encountered over a period of months. According to health officials, this points to some spread among closely related individuals in London. But no real cases of polio have yet been identified, nor would there be any reports of the rare but serious symptoms reported BBC.