Children in London are being offered a polio vaccine booster following the discovery of the virus in sewage in the north and east of the UK capital.

This kind of insight from sewage is known as wastewater-based epidemiology (WBE) and involves carrying out analysis on samples taken from sewage works. It is proven to be an effective way of identifying exposure to pathogens in a population, and during the coronavirus pandemic WBE has come into its own, helping health authorities around the world identify outbreaks of Covid19 even before they reach the attention of service providers.

Earlier this year, poliovirus was collected from the Beckton sewage treatment works in east London and further sampling undertaken by the UK Health Security Agency (UKHSA) and the Medicines & Healthcare Products Regulatory Agency (MHRA) has now identified at least one positive sample of the poliovirus. The agencies say it is currently present in parts of eight London boroughs: Barnet, Brent, Camden, Enfield, Hackney, Haringey, Islington and Waltham Forest.

As a result, the Joint Committee on Vaccination and Immunisation (JCVI) has advised that a targeted inactivated polio vaccine (IPV) booster dose should be offered to all children between the ages of one and nine in all London boroughs. The Committee says it will ensure a high level of protection from paralysis and help reduce further spread of the virus.

Dr Vanessa Saliba, consultant epidemiologist at UKHSA, said: "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. This is why the virus is spreading in these communities and puts those residents not fully vaccinated at greater risk.

"Polio is a serious infection that can cause paralysis but nationally the overall risk is considered low because most people are protected by vaccination. The last case of polio in the UK was in 1984, but decades ago before we introduced the polio vaccination programme around 8,000 people would develop paralysis every year.

"It is vital parents ensure their children are fully vaccinated for their age. Following JCVI advice all children aged one to nine years in London need to have a dose of polio vaccine now – whether it’s an extra booster dose or just to catch up with their routine vaccinations. It will ensure a high level of protection from paralysis. This may also help stop the virus spreading further."

The NHS in London will contact parents when it is their child’s turn to come forward for a booster or catch-up polio dose and advises parents to take up the offer as soon as possible. The programme will start with the areas affected, where the poliovirus has been detected and vaccination rates are low. This will be followed by rapid rollout across all boroughs.

UKHSA, working with MHRA, has already increased sewage surveillance to assess the extent of spread of the virus and are currently sampling eight sites across London. A further 15 sites in London will start sewage sampling in mid-August, and 10 to 15 sites will be stood up nationally to determine if poliovirus is spreading outside of London.