What does the detection of polio samples in London wastewater mean? Is there a real danger, and could it spread to the rest of the UK? Journalist Kaye McIntosh investigates.
Polio virus, which causes a deadly disease that used to paralyse tens of thousands of children worldwide every year in the 1950s and 60s, is now spreading in London, New York and Jerusalem. It’s happening for the first time in decades, spurring catch-up vaccination campaigns.
A type 2 virus, related to the strain in the live oral vaccine used overseas, was first identified in samples from sewage works in north London in February. The virus has since been found in eight more treatment plants in different districts of the capital. Decades ago, before the introduction of the polio vaccination programme, up to 8000 people would develop paralysis due to polio every year in the UK (NHS Scotland, 2022).
The UK Health Security Agency (UKHSA) has declared a national enhanced polio incident response and said the London virus is spreading. The level of infectious agent found, as well as the high genetic diversity among the samples, suggests transmission in separate groups of people – not just close contacts of the original infected person. In London, though, no clinical cases of the disease have been reported (Department of Health and Social Care, 2022).
In New York, however, one unvaccinated man has developed paralysis from polio (Centers for Disease Control and Prevention, 2022). In March, the World Health Organization (WHO) also reported a case of paralysis in an unvaccinated three-year-old child in Israel (WHO, 2022).
Polio was declared eradicated in Europe in 2003, but the virus is occasionally detected in waste water from people who have been vaccinated with live virus abroad. This country uses an inactivated vaccine, which doesn’t carry the risk of transmission.
What does this mean?
‘The main worry here is the genetic connectedness of the strains found in the sewage in north London, as it shows transmission in a group and not just a single “excreter”,’ says Professor Beate Kampmann, director of the vaccine centre at the London School of Hygiene and Tropical Medicine.
This finding, she adds, is a warning that ‘we must not be complacent and it reminds us all how vital the comprehensive use of vaccines against polio is.’
Janet Taylor, a public health nurse manager at the South Eastern Health and Social Care NHS Trust in Northern Ireland, and CPHVA Executive chair, says: ‘You would have thought it was highly unlikely we’d see polio detected in the UK again. This emphasises the importance of immunisation. People can get lulled into a false sense of security because we don’t see these diseases around any more.’
Help to combat myths
Janet believes community practitioners have a vital role to play in combating vaccine misinformation, stressing that… ‘school nurses who deliver the vaccination programme and health visitors who give out information can make parents feel comfortable and secure that they are making an informed choice.’
Dr Vanessa Saliba, consultant epidemiologist at the UKHSA, agrees: ‘Healthcare professionals in the community are incredibly important ambassadors for the benefits of vaccination and are key to supporting local efforts to bolster uptake among under-vaccinated communities. Without high vaccine uptake, viruses will continue to make their way back.’
Beate says polio vaccine coverage in London is only 86%, creating ‘a potential pool of susceptibles’.
Low vaccination rates are caused by a mixture of factors. Health inequalities affect vaccine coverage for routine childhood immunisation, Vanessa says, as well as ethnic and socio-economic diversity. ‘London’s population is very mobile,’ she adds, ‘with many families moving in and out of the city and between boroughs – families who may not immediately register with a new GP and can then miss vaccination appointments.’
Covid-19 is another element; during the pandemic, some children under 5 missed out on routine vaccinations. Up to August 2021 only 86.5% of infants completed the course of hexavalent vaccine, which includes polio, by six months of age – 2.4 percentage points lower compared to August 2019. Just 87.7% of infants were vaccinated with MMR1 by 18 months of age – 0.9 percentage points lower than August 2019 (UKHSA, 2021a).
In August, the JCVI advised an urgent extra vaccination strategy booster campaign should be launched in London. Doses for children are being rolled out to more than 40 sites in the capital, with clinics held in hospitals, community pharmacies and even shopping centres. Children aged five-nine years are being invited, while one-four year olds can get catch-up doses at their GP practice.
Jane Clegg, chief nurse at NHS London, says, ‘The NHS has now contacted all parents in London with children aged between one to nine years old to come forward for a booster or catch-up dose of the polio vaccine, and we encourage them to take up the offer as soon as possible.’
‘We must not be complacent and the appearance of multiple sources in London reminds us all how vital the comprehensive use of vaccines against polio is’
Sewage surveillance
Wastewater testing played a vital role during the Covid pandemic. The Environmental Monitoring for Health Protection (EMHP) programme picked up where Covid-19 was circulating, detecting it even in asymptomatic people (UKHSA, 2021b). The sewage from tens of thousands of homes provided vital clues as to where the virus was spreading.
The programme, run by UKHSA with Defra and the Environment Agency, covered 75% of the population of England. It ended in March, to the disappointment of public health specialists.
Dr Philip Minor, former head of the division of virology at the National Institute for Biological Standards and Control, and now an independent consultant, says: ‘Sewage surveillance is cheap. Using modern sequencing technology, it is possible to look for any virus that may be shed in the faeces in sufficient amounts. With the power of modern sequencing methods you do not even need to know what you are looking for. In my opinion there should be major ongoing investment in sewage surveillance in preparing for pandemics.’
While the EMPH has now ended, other UK nations have taken up the baton. Northern Ireland has announced £3.8m for wastewater surveillance at 30 sites.
Wales has provided £4m to fund a six-month pilot project at sewage treatment plants.
The UKHSA says it will continue to monitor wastewater for polio under a separate programme, part of the WHO’s Global Eradication Initiative, which is how polio was detected earlier this year.
Polio across the UK
Vanessa explains: ‘We are now expanding sewage sampling nationally to monitor any spread outside of London. Locations have been chosen based on their links to countries where polio virus is still found, or where live oral polio is used, as well as pockets of under-vaccinated communities and areas adjacent to where polio virus has been detected in London.’
Sites for the new surveillance programme include 19 towns and cities from the North East to the West Midlands and the South East, and from the West of England to the south coast (see map below).
Scotland: low risk
Testing in Glasgow has not detected any polio virus. There are no plans for any catch-up programme in Scotland. Dr Nick Phin, clinical director at Public Health Scotland, says: ‘The risk to the public overall is extremely low. Scotland has high vaccination uptake rates which we need to maintain in order to reduce the risk of infections occurring.’
He advised worried parents to check their child’s red book or call their GP surgery to see if vaccinations are up to date, adding, ‘We strongly encourage parents and carers to ensure that children receive all recommended vaccinations as soon as they are eligible.’
Wales
Public Health Wales said there is no evidence that vaccine-derived virus is circulating. But NHS Wales will be running a catch-up campaign for all under-fives who have missed doses over the next few months, together with a public information campaign on childhood vaccines.
Northern Ireland
Nothing has been announced to date. Polio vaccination rates are over 96% (Health and Social Care Northern Ireland, 2022).
The last resort
Public health specialists say vaccination is the answer to prevent polio being transmitted before it causes any clinical cases in unvaccinated people. But, if all else fails, there is also a new tool at hand. A novel type of oral polio vaccine (nOPV) has been designed to prevent mutations and to be used in emergencies to control outbreaks around the world. Beate says: ‘This could be an option if we really do see wider spread.’ However, it is intended to be kept for emergency use only.
Resources
Inactivated polio vaccine (IPV) booster campaign: information for healthcare practitioners bit.ly/UKHSA_polio_campaign
Booster campaign vaccination London sites nhs.uk/conditions/polio/vaccination-sites
WHO Global Advisory Committee on Vaccine Safety sub-committee on novel polio vaccine safety bit.ly/WHO_polio_safety
For a reminder of the facts on polio, see Back to basics
References
Department of Health and Social Care. (2022) Joint committee on vaccination and immunisation statement on vaccination strategy for the ongoing polio incident. See: gov.uk/government/publications/vaccination-strategy-for-ongoing-polio-incident-jcvi-statement/joint-committee-on-vaccination-and-immunisation-statement-on-vaccination-strategy-for-the-ongoing-polio-incident (accessed 11 October 2022).
Link-Gelles R, Lutterloh E, Ruppert PS et al. (2022) Public Health Response to a Case of Paralytic Poliomyelitis in an Unvaccinated Person and Detection of Poliovirus in Wastewater — New York, June–August 2022. Morbidity and Mortality Weekly Report 71(33): 1065-068.
Public Health Agency. (2022) Vaccination coverage. See: publichealth.hscni.net/directorate-public-health/health-protection/vaccination-coverage (accessed 11 October 2022).
Public Health Scotland. (2022) Poliomyelitis. See: hps.scot.nhs.uk/a-to-z-of-topics/poliomyelitis (accessed 11 October 2022).
WHO. (2022) Circulating vaccine-derived poliovirus type 3 – Israel. See: who.int/emergencies/disease-outbreak-news/item/2022-DON366 (accessed 11 October 2022).
UK Health Security Agency. (2021a) COVID-19: impact on childhood vaccinations: data to August 2021. See: gov.uk/government/publications/covid-19-impact-on-childhood-vaccinations-data-to-august-2021 (accessed 11 October 2022).
UK Health Security Agency. (2021b) Environmental Monitoring for Health Protection (EMHP); wastewater monitoring of SARS-CoV-2 in England: 1 June to 23 August 2021. See: gov.uk/government/publications/monitoring-of-sars-cov-2-rna-in-england-wastewater-monthly-statistics-1-june-to-23-august-2021/environmental-monitoring-for-health-protection-emhp-wastewater-monitoring-of-sars-cov-2-in-england-1-june-to-23-august-2021 (accessed 11 October 2022).
UK Health Security Agency. (2022) All children aged 1 to 9 in London to be offered a dose of polio vaccine. See: gov.uk/government/news/all-children-aged-1-to-9-in-london-to-be-offered-a-dose-of-polio-vaccine (accessed 11 October 2022).
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