LONDON — The U.K. is offering all children aged 1 to 9 a booster dose of the polio vaccine after further poliovirus has been found in sewage in the capital.
The committee advising the British government on vaccination has recommended that a booster dose be offered to children of those ages in all London boroughs. The government on Wednesday accepted the advice and the National Health Service will start contacting parents and guardians.
“I recognise parents and guardians will be concerned about the detection of polio in London, however I want to reassure people that nobody has been diagnosed with the virus and the risk to the wider population is low,” said Health Secretary Steve Barclay.
In recent months, cases of vaccine-derived polio have been detected in the U.S. and Israel.
The poliovirus that has been found in sewage in the boroughs of Barnet, Brent, Camden, Enfield, Hackney, Haringey, Islington and Waltham Forest is not wild virus but derived from the vaccine. It occurs if the weakened live virus in oral polio vaccines — which does not cause polio in the recipient, and is shed by vaccinated kids through their digestive system — circulates in under-vaccinated communities long enough for it to mutate into a version that resembles wild polio, regaining the ability to paralyze.
The U.K. Health Security Agency said today that, across London, childhood vaccination uptake is lower than in the rest of the country and that offering a booster dose to children will “ensure a high level of protection from paralysis and help reduce further spread of the virus.”
The level of poliovirus found, as well as the genetic diversity among the samples, suggests that there is a level of virus transmission in the areas where it’s been found, said the agency, indicating that “transmission has gone beyond a close network of a few individuals.” However, the agency said that the risk remains low to the national population as most people were protected through vaccination.
Countries like the U.S. and Belgium already offer a booster dose of the vaccine to prevent polio as part of their ordinary childhood vaccination schedule.
In July, New York confirmed the U.S.’ first case of polio nearly a decade with the health department urging unvaccinated people to get a jab. Like the sewage samples in the U.K., the U.S. case was also indicative of transmission from someone who received the oral polio vaccine. That vaccine is no longer used in the U.S. and hasn’t been used in the U.K. since 2004.
However, the oral vaccine is still used in some countries, particularly to respond to polio outbreaks. People can shed the vaccine virus in their feces for several weeks with vaccine viruses spreading in under-vaccinated communities through poor hand hygiene or water and food contamination.
In March, the World Health Organization was also notified of vaccine-derived poliovirus in Israel, with pediatric paralysis being detected in a child. Several other asymptomatic children in the country also tested positive for polio. Since the spate of cases, Israel has rolled out a vaccination campaign to ensure those under 18 are fully vaccinated.
Wild polio cases have decreased by more than 99 percent since 1988, according to the WHO. Currently, wild poliovirus affects Pakistan and Afghanistan.