Polio discovered in the UK - what is it and is there a risk to the public?

Almost a million children aged one to nine across London are to be offered a polio vaccine to try to prevent the spread of the virus.

Health officials warned there has been “some transmission” of the virus in the capital after detecting poliovirus in sewage samples.

What is polio?

Polio is a contagious virus that can be transmitted through coughs and sneezes, but also through food, water or objects that have been in contact with the faeces of someone infected with it.It can live in an infected person's throat for weeks without them suffering any symptoms.

Around 70% of people who have polio have no symptoms.

The last confirmed case of polio in the UK was in 1984 and it was declared eradicated in 2003.

In most cases it appears like the flu with mild symptoms, but in rare instances - more than one in 100 - it can affect the nerves in your spine and brain and cause paralysis.

This paralysis is usually in the legs and normally lasts a few weeks or months.

But it can be life-threatening if the paralysis affects the muscles in your neck that help with breathing.

For those who do suffer some form of paralysis, around 2 to 5% of children and 15 to 30% of adults die.

US President Franklin Roosevelt suffered from what is believed to have been polio in 1921, which left him needing to use a wheelchair for the rest of his life.

He founded a research centre for polio in 1938 which led to the development of the first vaccines against the virus.

The vaccines have effectively eradicated "wild polio" from the planet, and between 2018 and 2022 it was only reported in Afghanistan and Pakistan.

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What has been discovered in the UK?

The UKHSA, working with the Medicines and Healthcare products Regulatory Agency (MHRA), has found polio in sewage samples collected from the London Beckton Sewage Treatment Works, which serves around four million people in north and east London.

Since then the virus has been found in: Barnet; Brent; Camden; Enfield; Hackney; Haringey; Islington and Waltham Forest.

While it is normal for the virus to be picked up as isolated cases and not detected again, experts have raised the alarm after several genetically-linked viruses were found in samples between February and May.

The strain of polio is not the natural "wild" strain, but instead, it is a weaker form of the virus that is included in the oral vaccination.

ITV News' Science Editor Deborah Cohen explains what the discovery of polio in sewage in North and East London means.

It is believed someone who received the oral vaccination brought the weakened case to the UK from abroad and then shed traces of it in their faeces.

However, this weakened polio has since evolved into ‘vaccine-derived’ poliovirus type 2 (VDPV2).

VDPV is a strain of the weakened poliovirus, that was initially included in the oral polio vaccine, which has changed over time and behaves more like the “wild” or naturally-occurring virus.

This means it can spread more easily to people who are unvaccinated and who come into contact with the faeces or coughs and sneezes of an infected person.The UKHSA is working on the theory that a person vaccinated abroad with the polio vaccine – possibly in Afghanistan, Pakistan or Nigeria – entered the UK early in 2022 and was shedding the virus.That person has now passed it onto other, closely linked individuals in north-east London, who in turn are shedding the virus into their faeces.

Which jab will be offered?

The UK stopped using live oral polio vaccine in 2004 and switched to inactivated polio vaccine, so this is the vaccine that will be offered to children.

Is there anything to worry about?

For the vast majority of the UK, there is nothing to worry about. All children in the UK have been offered the polio vaccine for decades.

On August 10, officials announced that a rapid vaccination programme will be launched among those aged one to nine in London, where there are lower levels of uptake of the vaccine.

The NHS in London will contact parents when it's their child’s turn to get the vaccine, with parents urged to take up the offer “as soon as possible."

The programme will start in the areas where the virus has been detected in sewage and then be extended across all London boroughs.

The virus has not yet been found outside London but officials are stepping up surveillance across the rest of the country.

When are children supposed to have the polio vaccine?

The polio vaccine is usually given when a child is eight, 12 and 16 weeks old as part of the 6-in-1 vaccine.

Alongside polio, the 6-in-1 vaccine protects babies against diphtheria , hepatitis B Hib (Haemophilus influenzae type b) , tetanus and whooping cough.

The polio vaccine is given again at three years and four months old as part of the 4-in-1 pre-school booster, and at 14 as part of the 3-in-1 teenage booster.

Wasn’t there a case in New York?

The UK Health Security Agency said that it is working with health agencies in New York and Israel to investigate whether there are links between “polio incidents” in these countries.

Officials in New York announced that they had a confirmed case of paralytic polio in an unvaccinated person in July.

And global health officials have now confirmed the case is “genetically linked” to the samples from sewage detected both in London and Jerusalem.