East and North London Sewage Contains Poliovirus
The UK Heath Security Agency (UKHSA) announced today that poliovirus samples had been found in sewage collected from the London Beckton Sewage Treatment Works between February and May 2022.
The UKHSA confirmed on June 22, 2022, investigations determined the poliovirus has evolved and is now classified as a ‘vaccine-derived’ poliovirus type 2 (VDPV2), which can cause serious illness in under-immunized people.
The detection of a VDPV2 suggests there has been some spread between closely-linked individuals in North and East London and that they are now shedding the type 2 poliovirus strain in their feces.
However, VDPV2 has only been detected in sewage samples and no associated cases of paralysis have been reported.
‘As part of routine surveillance, it is normal for 1 to 3 ‘vaccine-like’ polioviruses to be detected each year in UK sewage samples, but these have always been one-off findings that were not detected again,' says the UKHSA.
These previous detections occurred when an individual vaccinated overseas with the live oral polio vaccine returned or traveled to the UK and briefly ‘shed’ traces of the vaccine-like poliovirus.
Dr. Vanessa Saliba, a Consultant Epidemiologist at UKHSA, commented in a related press release, “Vaccine-derived poliovirus is rare, and the risk to the public overall is extremely low.”
“Most of the UK population will be protected from vaccination in childhood, but in some communities with low vaccine coverage, individuals may remain at risk.”
The World Health Organization considers the UK polio-free, with a low risk for polio transmission due to the high level of vaccine coverage across the population.
However, vaccine coverage for childhood vaccines has decreased nationally and especially in parts of London over the past few years, so the UKHSA is urging people to check they are up to date with their vaccines.
Jane Clegg, the Chief nurse for the NHS in London, added, “The majority of Londoners are fully protected against polio and won’t need to take any further action.”
“But the NHS will begin reaching out to parents of children under 5 in London who are not up to date with their polio vaccinations to invite them to get protected.”
To better determine risks, wastewater surveillance is being expanded in London to assess the extent of transmission and identify local areas for targeted action.
And healthcare professionals have been alerted to these findings so they can promptly investigate and report anyone presenting with symptoms that could be polio, such as paralysis.
A similar finding was confirmed in Israel in April 2022.
In response, Israel's Health Ministry launched a polio vaccination campaign to reach about 2.5 million children.
The Global Polio Eradication Initiative says, ‘Wild poliovirus type 1 remains endemic in two countries, Afghanistan and Pakistan.’
‘Until poliovirus transmission is interrupted in these countries, all countries remain at risk of polio importation, especially vulnerable countries with weak public health and immunization services and travel or trade links to endemic countries.’
To notify international travelers of their potential polio risks, the U.S. CDC issued Alert - Level 2, Practice Enhanced Precautions for Africa, Asia, and Eastern Europe in April 2022.
‘Before travel to any high-risk destination, the CDC recommends that adults who previously completed the full, routine polio vaccine series receive a single, lifetime booster dose of polio vaccine.’
Since the 2016 withdrawal of the Sabin polio vaccine virus type 2 and the globally synchronized switch from trivalent OPV to bivalent OPV in all OPV-using countries, bOPV and injectable inactivated poliovirus vaccine has been used in routine immunization programs worldwide, says the CDC.
In November 2020, the WHO granted Emergency Use Listing for the novel OPV2 (nOPV2) vaccine which was designed to be more genetically stable than the Sabin strain and less likely to revert to neurovirulence.
Since that time, approximately 525 million nOPV2 doses have been released for use in 21 countries as of May 5, 2022.
Travel vaccination clinics and pharmacies can offer polio vaccination recommendations in the USA.
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