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Dozens of polio vaccination centres have sprung up across London as health bosses urge parents to get their children vaccinated against the contagious virus polio.
The virus was found in sewage samples collected from the London Beckton Sewage Treatment Works, which serves around four million people in north and east London.
Since then the virus was discovered in Barnet; Brent; Camden; Enfield; Hackney; Haringey; Islington and Waltham Forest.
The NHS set up 40 vaccination centres across the capital to help "counteract the threat" and protect as many children as possible.
"We're really encouraging parents to come forward with their children who are not vaccinated at all, and also those who might have missed their polio vaccine during the Covid pandemic," said Senior NHS Clinical Advisor Dr Tehseen Khan.
"So those children that are fully up to date it will be an additional dose of the vaccine to help protect them and it's eligible for all children from the ages of one to nine, and here we're seeing children from the ages of five to nine at the hospital sites.
'Some way to go,' Dr Tehseen Khan told ITV News in getting children vaccinated
Dr Khan said polio was a serious virus and it was important parents acted now to keep their family safe.
"We managed to eradicate polio in this country back in the 1980s but it is still prevalent in some parts of the world and because there are some unvaccinated children it can spread again through travel and we have seen that in some cases in New York and Israel.
"I encourage all parents to bring their children to have their polio vaccine on time," urged Dr Khan.
Dr Khan said there were a number of reasons why uptake of the vaccine was low including the coronavirus pandemic when parents may have stayed away from GP surgeries.
Health officials said it was important they caught up with "as many children as possible now".
Parents at the surgery at London's Homerton Hospital said it was important to protect their family because of the potentially serious symptoms of the virus.
One parent told ITV News: "It was quick and easy, the nurse was very nice and they got to do some colouring in, and we didn't even notice the vaccines were already done. I think getting the vaccine is just what we are all meant to do to make sure to make sure infections don't re-emerge."
Why has polio returned to the UK?
Despite the eradication of wild poliovirus, in some countries vaccines are given with oral drops. They contain a weakened form of the virus which develops immunity and builds antibodies. The virus in the oral vaccine is also excreted which means if a population is under-immunised it can continue to circulate. On very rare occasions, the vaccine-virus can mutate into a form that can paralyse, known as a circulating vaccine-derived poliovirus, which behaves more like wild polio. The virus is spread by poor hand hygiene, in particular when an infected person does not wash their hands after using the toilet and then touching food or water consumed by others and, less commonly, through coughing and sneezing.
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