All children between the ages of one and nine in London are to be offered a polio booster dose after polio viruses derived from the oral polio vaccine were detected in sewage water in north and east London, UK health authorities said on Wednesday.
The children will be offered a targeted inactivated polio vaccine (IPV) booster dose as type 2 vaccine-derived poliovirus were found in sewage water. The UK Health Security Agency (UKHSA) said nationally the overall risk of paralytic polio is considered low because most people are protected from this by vaccination.
The targeted action in the UK capital is being undertaken on the advice of the independent Joint Committee on Vaccination and Immunisation (JCVI) to ensure a high level of protection from paralysis and help reduce further spread of the virus. 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, Dr Vanessa Saliba, Consultant Epidemiologist at UKHSA.
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 said. The UKHSA said it is vital parents take up the offer and ensure their children are fully vaccinated for their age. Following the latest advice, all children aged one to nine years in London need to have a dose of polio vaccine right away whether it's an extra booster dose or just to catch up with their routine vaccinations.
While the majority of Londoners are protected from polio, the NHS [National Health Service] will shortly be contacting parents of eligible children aged one to nine years old to offer them a top-up dose to ensure they have maximum protection from the virus, said Jane Clegg, Chief Nurse for the NHS in London.We are already reaching out to parents and carers of children who aren't up to date with their routine vaccinations, who can book a catch-up appointment with their GP [general practitioner] surgery now and for anyone not sure of their child's vaccination status, they can check their [vaccine log] Red Book, she said.
The targeted programme will start with the areas affected, where the poliovirus has been detected earlier this year and vaccination rates are low. This will be followed by rapid rollout across all boroughs of London. The booster dose will be in addition to the NHS childhood vaccination catch-up campaign across London, where childhood vaccination uptake is lower than the rest of the country. The NHS said it's important all children aged one to nine even if up-to-date with their vaccinations accept this vaccine when offered to further strengthen their protection against the poliovirus.
Following the findings earlier this year of type 2 poliovirus (PV2) collected from the Beckton in east London sewage treatment works, further upstream sampling undertaken by the UKHSA and the UK's Medicines and Healthcare products Regulatory Agency (MHRA) has also identified at least one positive sample of the poliovirus, currently present in parts of eight other London boroughs. The health agencies said they have increased sewage surveillance to assess the extent of spread of the virus and a further 15 sites in London will start sewage sampling in mid-August.
The sampling has also detected the virus in lower concentrations and frequency in areas adjacent to the Beckton catchment area to the south (immediately below the Thames) and to the east of Beckton. However, it is not clear whether the virus has established itself in these areas or if the detections are due to people from the affected area visiting these neighbouring areas, they said.
The level of poliovirus found and the high genetic diversity among the PV2 isolates suggests that there is some level of virus transmission in the tested boroughs, which may extend to the adjacent areas. This suggests that transmission has gone beyond a close network of a few individuals, the UKHSA said. A total of 116 PV2 isolates have been identified in 19 sewage samples collected in London between February 8 and July 5 this year, but most are vaccine-like virus and only a few have sufficient mutations to be classified as vaccine derived poliovirus (VDPV2).
VDPV2 is of greater concern as it behaves more like naturally occurring wild polio and may, on rare occasions, lead to cases of paralysis in unvaccinated individuals. UKHSA said it is working closely with health agencies in New York and Israel alongside the World Health Organisation (WHO) to investigate the links between the poliovirus detected in London and recent polio incidents in these two other countries.