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The UK Health Security Agency (UKHSA) have announced that, following the discovery of vaccine-derived poliovirus in sewage in north and east London, the Joint Committee on Vaccination and Immunisation (JCVI) advise that children aged 1-9 in London are offered a polio vaccine booster dose.
Prof David Heymann, Professor of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, said:
“The U.K. has a comprehensive and highly efficient system for detecting unexpected infections that come from elsewhere, as well as for keeping track of those infections that are endemic in the country. The surveillance system is linked to genetic sequencing and it is this system that identified the unexpected vaccine derived polio virus in the sewage system. Genetic sequencing is a powerful tool, and since the first vaccine derived polio virus was found there have been many more, and the various mutations in genetic sequence suggest that many different neighbourhoods are having transmission in populations that are poorly covered with vaccine. This should give us all a wake up call – vaccine derived polio virus is circulating in many countries around the world – including in parts of the UK and the US. Though not all children and adults who are infected with a vaccine derived polio virus become paralysed, those who have not been fully vaccinated are at risk of being paralysed – and they are also the persons who continue to facilitate transmission and the outbreaks that are occurring in the U.K. Vaccination against polio is therefore both a personal protective measure and an individual responsibility to protect the communities in which we live from vaccine derived polio transmission.”
Prof Nicholas Grassly, Professor of Vaccine Epidemiology, Imperial College London, said:
“Testing of sewage confirms that vaccine-derived poliovirus is spreading in London. If it continues to spread, it will result in cases of paralysis in unvaccinated individuals. It is therefore of paramount importance that children are up to date with their polio vaccines. The vaccination campaign in London targeting children 0-9 years old will help achieve this, in addition to limiting the spread of the virus.
“The poliovirus circulating in London is genetically linked to that detected in sewage in Israel and in a paralytic case in New York. The international spread of poliovirus is considered a public health emergency by the World Health Organisation. The national public health authorities in the UK are therefore taking urgent action to vaccinate Londoners against this virus and to enhance surveillance in other cities.
“The campaign with inactivated poliovirus vaccine (IPV) will protect individuals from paralysis. It will also limit circulation of the virus and it is hoped it will bring this outbreak under control. However, IPV is less effective against virus transmission than the oral poliovirus vaccine (OPV) and it is possible that OPV, last used in the UK in 2004, may need to be reintroduced to eliminate transmission of this virus.”
Prof David Salisbury, Associate Fellow, Programme for Global Health, Chatham House; and Chair, WHO Global Commission for Certification of Polio Eradication, said:
“I think the UKHSA is trying to explain the difference between vaccine-like and vaccine-derived poliovirus – it’s a differentiation between vaccine virus that is very close to the original vaccine virus, and more distant virus that has mutated to neurovirulent (with the potential to cause paralysis) and more transmissible. From the statement it sounds like the samples found were mostly vaccine viruses, close to what is in the vaccine; and only a few were more distant, neurovirulent and transmissible.
“In London it is just good luck that nobody has been paralysed from these viruses that have been picked up – the situation has been helped by the number in the population who have been vaccinated previously, thus reducing the risk. Those who are vaccinated are well protected – it is those people who are unvaccinated or under-vaccinated who are at risk.
“It is it a sensible precaution to offer a booster vaccine to children aged 1 to 9 in London – and worth pointing out that those children who have not had polio vaccine have missed out on other vaccinations too. Hopefully, people will use this opportunity to check all their children’s vaccinations.
“Whether the increased surveillance at more sites announced today will be enough depends on how many other sites are being set up. This should have been done months and indeed years ago. The UK polio surveillance is not sufficiently robust. Once in place, the additional sites should be sufficiently funded to provide permanent regular reporting.”
Dr David Elliman, consultant paediatrician at Great Ormond Street Hospital, said:
“In June, the information that vaccine derived polio virus (VDPV2) had been found in sewage in North London was a wake-up call that we cannot be complacent about vaccination rates, particularly in London. The report of a case of polio in New York City in July of this year, followed by the announcement a week or so later that VDPV2 had been found in wastewater in a local county reminded us all that, although polio was down, it was far from out.
“The news that numerous samples of sewage from different parts of North London have been found to have VDPV2 genetically similar to each other, is a strong indication that the virus is circulating in the community. So far, there have been no reports of polio disease in this country, but this is a significant risk in those who are not up to date with their vaccinations. This is very concerning.
“Already GPs and Practice Nurses had been working hard to contact the parents of children who were not fully immunised and offering them the chance to catch up. Any parent who knows one of their children is behind with their vaccinations should contact their General Practice as soon as possible.
“As a precautionary measure, the Joint Committee on Vaccination and Immunisation has recommended that all children aged 1-9 years old, in London, should be offered a dose of a polio-containing vaccine, if they have not had one in the recent past. This is to ensure they have the best possible protection and includes children who are fully up to date with their vaccinations. If parents have a child of this age, who is up to date with their vaccines, they should wait until their General Practice calls them.
“Who amongst the 1-9 year olds should get the vaccine is a little complicated and is laid out at: https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/1097368/UKHSA_12370_IPV_booster_algorithm_poster.pdf.”
Prof Sir Andrew Pollard, Chair of the JCVI, said:
“The finding of polio in sewage, which indicates that the virus is transmitting between people in London, requires urgent action to make sure that the unvaccinated and those who have missed doses are protected from this paralysing virus. By acting quickly to close the immunity gap, and boosting all children under 10 years of age we hope that further spread can be curtailed.”
Dr Kathleen O’Reilly, Associate Professor in Statistics for Infectious Disease and expert in Polio Eradication, London School of Hygiene & Tropical Medicine, said:
“The announcement of a polio booster dose in parts of London follows on from previous findings where poliovirus was detected in sewage. Poliovirus has continued to be detected in sewage, and this has led JCVI to recommend a polio vaccine booster in children under 10 years of age. I think that the polio booster is a very good plan – sewage surveillance has provided us with information about poliovirus circulation and a critical opportunity to vaccinate and prevent disease.
“In these investigations, ‘vaccine-like’ and ‘vaccine-derived’ poliovirus has been detected in several sewage samples from the north London area over a number of months. The virus classification is based on genetic sequencing; all samples seem to be related to each other and suggests infections have gone beyond a few individuals. The sewage sampling has been extended to establish areas that have limited or no evidence of circulation, but has also included testing smaller catchment areas to better refine the extent of circulation. These investigations of sewage catchments for poliovirus have been very helpful in understanding the epidemiology of this incident, but also illustrates that circulation is wider than originally thought. Based on this information, sewage sampling elsewhere in the country is needed, and opportunistic stool sampling is needed to better understand who is at risk to help target vaccination activities. An additional 15 sewage sites across the country is a manageable number to test. Selection of these sites has been “risk based” which has been carried out by balancing local polio vaccination coverage and identifying large catchment areas (I published similar work on this with UKHSA colleagues some years ago https://pubmed.ncbi.nlm.nih.gov/32398193/ ).
“As the evidence for circulation of poliovirus has increased, the recommendation to be up to date with polio vaccines has been extended to include a booster dose in children under 10 years of age in London. Vaccination is the best course of action to prevent disease, and the decision for a booster dose is great and is not especially different to that taken by other high-income countries. The UK vaccinates against polio using the ‘inactivated’ vaccine (called the IPV) where there is no risk of onward spread and the vaccine is very safe. As the epidemiology of this situation progresses, the use of other vaccines that are better designed to prevent infection may need to be explored. So far limited details of the programme for the booster dose are available but I expect that in the coming weeks more will be available – it is likely to include many different groups that can offer vaccinations, and central to its success will be effective communication and making access easy for everyone who is eligible for a booster dose.
“Vaccine-derived poliovirus is present in many countries across the world, especially within the African continent and some countries in Asia. The origin of vaccine-derived poliovirus is from certain versions of the live oral polio vaccine, which are used in a small number of countries. The poliovirus circulating in London is genetically related to virus found in a recent polio case in the USA, and in Israel. Further investigation is needed to fully understand how they are connected, but it does illustrate that this virus has the potential to cause disease, especially in poorly vaccinated communities. Until all polioviruses are stopped globally, all countries are at risk, highlighting the need for polio eradication, and continued global support for such an endeavour.”
Declared interests
Prof Nicholas Grassly: “No conflicts.”
Prof David Salisbury: “No conflicts.”
Dr Kathleen O’Reilly: “Supporting UKHSA in the response and is a committee member of the WHO polio SAGE.”
For all other experts, no reply to our request for DOIs was received.