British health authorities say they are cooperating with counterparts in Israel and the US to trace the source of polioviruses found in sewage samples from neighborhoods in north and northeast London, launching a vaccination drive to boost immunity in kids.
In a statement on Wednesday, Britain’s Health Security Agency said it had detected polioviruses derived from the oral polio vaccine in sewage water from eight boroughs of London, but had not identified any cases.
Its analysis of the virus samples suggested “transmission has gone beyond a close network of a few individuals” but that it had not found anyone infected with the virus. According to the World Health Organization, only one in 200 polio infections leads to paralysis; most people don’t show any symptoms.
The UK health agency said it was “working closely with health agencies in New York and Israel alongside the World Health Organization to investigate the links between the poliovirus detected in London and recent polio incidents in these two other countries.”
Israel’s Health Ministry did not immediately respond to a request for comment on the investigation.
Officials in New York announced last month they had detected polio in an Orthodox Jewish man from Rockland County, marking the first case of polio in the US in nearly a decade.
The Global Polio Eradication Initiative said on July 28 that the case was genetically linked to virus samples found in London and at the Sorek wastewater treatment plant in Israel.
Officials in Rockland and Orange counties, areas north of New York City with a large and growing Haredi population, later said virus traces had been found in sewage samples there.
Israel diagnosed its first case in decades in March, in a 4-year-old from Jerusalem. Several other asymptomatic cases were found in other children, and health authorities launched a national vaccination drive that they said raised the immunization rate to 96 percent in infants.
No link has been confirmed between the virus samples and the Jewish community. However, authorities in both New York and the UK noted that the virus was being found in area with lower rates of vaccination.
“We know the areas in London where the poliovirus is being transmitted have some of the lowest vaccination rates,” said Dr. Vanessa Saliba, a consultant epidemiologist at the UK Health Security Agency. “This is why the virus is spreading in these communities and puts those residents not fully vaccinated at greater risk.”
The other boroughs were identified as Brent, Camden, Enfield, Haringey, Islington and Waltham Forest.
Ultra-Orthodox communities often have below-average vaccination rates. In 2018 and 2019 Jerusalem and Rockland County both saw measles outbreaks thought to have been fueled by vaccine hesitancy among Haredi Jews.
The British health agency said it will begin offering a polio booster dose to children aged 1 to 9 in London to bolster inoculation against the disease.
“This will ensure a high level of protection from paralysis and help reduce further spread,” the agency said. Most people across Britain are vaccinated against polio in childhood. It said the risk to the wider population was low.
Polio is a disease often spread in water that mostly affects children under 5. It has mostly been wiped out from developed countries, but outbreaks remain in Pakistan, Afghanistan and parts of Africa. Initial symptoms include fever, fatigue, headache, vomiting, and muscle stiffness. Among people paralyzed by the disease, death can occur in up to 10% of cases when their breathing muscles become paralyzed.
In rare cases, the live virus contained in the oral polio vaccine used in the global effort to eradicate the disease can mutate into new forms potent enough to trigger new outbreaks. The vaccination booster effort in London will use injected polio vaccines that do not carry that risk.