Polio describes a potentially life-threatening disease triggered by a poliovirus. The last natural polio infection was recorded in 1984 in the UK, with the country being declared polio-free in 2003. Now, routine surveillance found traces of this virus in London sewage.
Dr Harriss explained that an old type of polio vaccination that is no longer used in the UK might be to blame for these traces.
He said: “In some parts of the world, we still use a form of vaccine which is on a sugar cube. Those older people, who are watching, will remember.
“And that’s a live virus which sits in your gut for a few weeks, your body makes antibodies and you’re protected from that.
“The trouble is wherever that is still used, the virus tends to sit in the gut and it can mutate and it very rarely mutates to a form that causes illness.
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“So maybe one in a billion children, who were given that sugar cube, may get ill from the vaccine.
“And when a person comes to the UK, having recently had that vaccine on a sugar cube, they can still seed – basically poo out – tiny amounts of the virus which is what was picked up.”
The concern regarding the samples is that there might have been some spread in northeast London within a family or a small community.
“There might have been some transmission in people this way, no symptoms, no illness, but the virus might have found a few people to spread amongst themselves,” Dr Harriss added.
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