A polio vaccine booster program has been announced in the United Kingdom targeting all London children under the age of 10. The program comes after more detections of poliovirus in London’s wastewater indicate the virus is spreading undetected throughout the city.
Back in June, the UK Heath Security Agency (UKHSA) reported finding several samples of “vaccine-derived” poliovirus type 2 (VDPV2) in a single London wastewater treatment center. The finding was important as the detections were spread across several months and genetic testing of the samples suggested a degree of community transmission had occurred between several individuals.
Now, a follow-up report from the UKHSA has announced a city-wide polio booster vaccine program for all children under the age of 10. The booster program will use a polio vaccine containing an inactivated form of the virus and will be offered to all children, including those who have completed their primary three-dose polio vaccination protocol as a newborn.
The urgency of the new booster program follows new reports of polio in wastewater samples from at least eight more boroughs in London. Up to early July, the UKHSA reports 116 type 2 poliovirus (PV2) isolates have been identified.
“The level of poliovirus found and the high genetic diversity among the PV2 isolates suggests that there is some level of virus transmission in these boroughs which may extend to the adjacent areas,” a UKHSA statement said. “This suggests that transmission has gone beyond a close network of a few individuals.”
Polio can often spread from person to person asymptomatically, and up to three-quarters of infections may not present in symptoms. Less than 1% of infections lead to polio paralysis, and so far no specific cases have been detected in London.
“No cases of polio have been reported and for the majority of the population, who are fully vaccinated, the risk is low,” said Vanessa Saliba, consultant epidemiologist at UKHSA. “But we know the areas in London where the poliovirus is being transmitted have some of the lowest vaccination rates. This is why the virus is spreading in these communities and puts those residents not fully vaccinated at greater risk.”
In early August, the Centers for Disease Control and Prevention (CDC) in the United States announced similar wastewater detections of poliovirus in a region north of New York City. Genomic analysis of the samples revealed links to samples found earlier in London and Israel.
Unlike the London detections, this US polio wastewater finding was accompanied by a positive human case. In this instance it was a young adult who had developed serious polio paralysis.
While these new polio detections are certainly unlike anything seen for decades in the UK and the US, it is important to stress we have safe and effective vaccines that can protect from severe disease. The recurrence of this viral infection is a potent reminder for all to be up to date on their vaccinations. Saliba is keen to remind people that before the advent of vaccines, thousands of people were paralyzed every year from polio.
“Polio is a serious infection that can cause paralysis but nationally the overall risk is considered low because most people are protected by vaccination,” added Saliba. “The last case of polio in the UK was in 1984, but decades ago before we introduced the polio vaccination program around 8,000 people would develop paralysis every year.”