London: UK health authorities on Wednesday issued a nationwide appeal to parents to ensure their children’s vaccines are up to date after the polio virus was discovered in sewer samples in London.
The UK Health Security Agency (UKHSA) said investigations are underway after several closely related viruses were found in sewer samples taken between February and May.
The virus has continued to evolve and is now classified as a vaccine-derived poliovirus type 2 (VDPV2), which in rare cases can cause serious illness, such as paralysis, in people who have not been fully vaccinated.
The discovery is cause for concern, as the last case of wild polio contracted in the UK was confirmed in 1984 and the UK was declared polio-free in 2003.
Vaccine-derived poliovirus is rare and the risk to the public is generally extremely low, said Dr. Vanessa Saliba, Consultant Epidemiologist at UKHSA.
Vaccine-derived poliovirus has the potential to spread, particularly in communities where vaccination rates are lower. In rare cases, it can cause paralysis in people who are not fully vaccinated, so if you or your child are not up to date on your polio vaccinations, it’s important that you check with your primary care physician, she said.
According to the UKHSA, the detection of a VDPV2 suggests that it is likely that there has been some spread between closely related individuals in north and east London and that they are now excreting the type 2 poliovirus strain in their feces.
The virus has only been found in sewer samples and no associated cases of paralysis have been reported, but investigations will aim to determine if there is community transmission.
The UKHSA said it is normal for one to three vaccine-like polioviruses to be detected in UK sewer samples each year as part of routine surveillance, but these have always been one-off findings that have not been detected again.
These previous detections occurred when a person who had been vaccinated abroad with the live oral polio vaccine (OPV) returned or traveled to the UK and briefly shed spores of the vaccine-like polio virus in his stool.
The majority of Londoners are fully protected against polio and will not need to take any further action, but the NHS will contact parents of children under five in London who are unaware of their polio vaccinations to invite them for be protected, said Jane Clegg, chief nurse for the NHS in London.
The UK is considered polio-free by the World Health Organization, with a low risk of polio transmission due to its high vaccination coverage among the population. However, childhood vaccine coverage has declined nationwide and especially in parts of London in recent years, so UKHSA is urging people to check they are up to date on their vaccines.
Wastewater monitoring is being expanded to assess transfer rates and identify local areas for targeted action. UKHSA said healthcare professionals have been made aware of these findings so that they can immediately investigate and report anyone showing symptoms that could be polio, such as paralysis.
The basic vaccination against polio is given to babies of two, three and four months. Three doses are needed to complete the basic course. In the UK it is given as part of the six-in-one vaccine.