“No cases of polio have been reported and for the majority of the population, who are fully vaccinated, the risk is low. But we know the areas in London where the poliovirus is being transmitted have some of the lowest vaccination rates,” Vanessa Saliba, an epidemiologist at the agency, said in a statement.
Polio was a fearsome, sometimes fatal scourge before an inactivated vaccine was first announced in 1955. The virus causes permanent paralysis in people who are not fully vaccinated in about 5 out of every 1,000 cases. The last case of polio in Britain was detected in 1984. Before mass vaccination, approximately 8,000 people in Britain developed paralysis from it every year.
The United States recently recorded its first case of polio in nearly a decade. The unvaccinated 20-year-old man from Rockland County sought treatment in a New York City hospital in June. He has since been discharged but is having difficulty walking.
The virus has also been detected in wastewater in the northern New York City suburbs of Rockland and Orange counties, which the New York State Department of Health said indicated wider local transmission.
Most of the U.S. population is protected against the disease through vaccinations in childhood. But in areas with low vaccination coverage, such as the ultra-Orthodox Jewish community in Rockland County, people who have not been immunized are at high risk. There is no treatment for polio.
British health officials said Wednesday that they are working closely with health agencies in New York and Israel, as well as the World Health Organization, to investigate any links between the poliovirus detected in London and recent incidents in the other two countries.
Since early February, 116 polioviruses had been identified in 19 wastewater samples from areas in northeast and central London. But only a few have sufficient mutations to be classified as vaccine-derived poliovirus, or VDPV2, the Health Security Agency said.
Health officials consider VDPV2 to be of “greater concern” because of the similarities with naturally occurring “wild” polio. Unvaccinated people who contract it have a small chance of becoming paralyzed.
Many countries provide an additional dose of the polio vaccine to children, British health officials said.
Lenny Bernstein contributed to this report.
