Millions of London children are to be offered a polio vaccine after the virus was again discovered in the city’s sewerage system.

In a statement, the UK Health Security Agency announced that following the discovery of type 2 vaccine-derived poliovirus in sewage in north and east London, 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 programme will start with the areas affected, where the poliovirus has been detected and vaccination rates are low, followed by rapid rollout across all boroughs.

The booster dose is in addition to the NHS childhood vaccination catch-up campaign across London, where childhood vaccination uptake is lower than the rest of the UK. The JCVI statement adds that it is important all children within the age group, even if up to date with their vaccinations, accept the vaccine when offered to further strengthen their protection against the poliovirus.

Following the finding in February this year of type 2 poliovirus collected from a sewage treatment works in east London, further upstream sampling undertaken by the UKHSA and the Medicines and Healthcare products Regulatory Agency (MHRA) has identified at least one positive sample of the poliovirus in eight London boroughs.

UKHSA consultant epidemiologist, Dr Vanessa Saliba, 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.”

She added: “Whether it’s an extra booster dose or just to catch up with their routine vaccinations, [the IPV jab] will ensure a high level of protection from paralysis. This may also help stop the virus spreading further.”