Polio virus detected in London sewage works prompts further analysis

A TYPE of polio virus derived from vaccines has been detected in London sewage samples, the World Health Organization and British health officials said last Wednesday (22), adding that more analysis was underway.

No human cases of polio have been found in Britain, where the crippling disease was fully eradicated two decades ago.

The WHO said in a statement that “type 2 vaccine-derived poliovirus (VDPV2)” had been found in environmental samples in the British capital.

“It is important to note that the virus has been isolated from environmental samples only,” it said, stressing that “no associated cases of paralysis have been detected.”

But it warned, “any form of poliovirus anywhere is a threat to children everywhere.”

Polio eradication expert Kathlene O’Reilly warned Wednesday that the discovery in the London sewage samples suggests “there may be localised spread of poliovirus, most likely within individuals that are not up to date with polio immunisations”.

“The most effective way to prevent further spread is to check vaccination histories, especially of young children, to check that polio vaccination is included,” she said.

Polio immunisation coverage in London stands at nearly 87 per cent, the WHO said.

Oral polio vaccine (OPV) replicates in the gut and can be passed to others through faecal contaminated water – meaning it won’t hurt the child who has been vaccinated, but could infect their neighbours in places where hygiene and immunisation levels are low.

Britain stopped using OPV in 2004, and British health authorities said it was likely that the virus found in the sewage samples had been imported by someone who was recently vaccinated with it abroad.

David Elliman, a consultant paediatrician at Great Ormond Street Hospital said parents sometimes ask why vaccines continue to be given against diseases that have been eliminated in the UK, like polio.

“The answer is that, although we are an island, we are not isolated from the rest of the world, which means diseases could be brought in from abroad,” he said.

“The finding of vaccine-derived polio virus in sewage proves the point.”

The UK Health Security Agency (UKHSA) said the virus isolates had been found in “collected from the London Beckton Sewage Treatment Works between February and June 2022.”