All you need to know about the rapid polio vaccination programme

Almost a million children in London are to be offered a polio vaccine.

Here are your questions answered about why health officials have launched the urgent vaccination programme.

– What has been announced?

Health officials have recommended that all children aged one to nine in London should be offered the polio vaccine – either as a catch-up dose or a booster – in a bid to stop the spread of the virus and prevent cases of paralysis.

Invitations will go out within four weeks to the parents of almost one million children.

– Why only in London?

The alarm was first sounded in June after poliovirus was discovered in Beckton sewage works. Since then the virus has been found in: Barnet; Brent; Camden; Enfield; Hackney; Haringey; Islington and Waltham Forest.

These areas will be targeted for vaccination first.

No samples have been detected outside of London.

And the vaccination rates are lower in the capital compared to the rest of the country.

Latest figures show that by the age of two in the UK, almost 95% of children have had the correct number of doses. However, this drops to just under 86.6% in London.

When it comes to the pre-school booster, just 71% of children in London have had it by the age of five.

– Which jab will be offered?

The UK stopped using live oral polio vaccine in 2004 and switched to inactivated polio vaccine.

– How can there be no confirmed cases yet poliovirus is being found in sewage works?

In countries dealing with live polio outbreaks, some people are offered the oral polio vaccine – which is safe, but uses a live virus.

As a result, health officials may detect traces of the vaccine-like poliovirus in faeces during routine sewage tests.

This is usually isolated and not detected again.

But there has been cause for concern in the most recent tests in London because the levels of polio found in the sewage and the “genetic diversity” of the samples found suggest that there has been “some virus transmission”, officials said.

However, there has not yet been an official case confirmed, just virus found in sewage.

– What’s concerning about that?

Some of the virus found in recent samples has been classified as 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 be spread more easily to people who are unvaccinated and who come into contact with the faeces or coughs and sneezes of an infected person.

On rare occasions, VDPV2 can lead to cases of paralysis in unvaccinated people.

– So how many people in London have it?

It is unclear, since February there have been 116 samples identified, but some of these could have come from the same person.

– 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.

– Parents are being asked to check whether their children are up to date with their vaccines – when are children supposed to have the jab outside of the booster/catch-up programme?

The polio vaccine is usually given on the NHS when a child is eight, 12 and 16 weeks old as part of the 6-in-1 vaccine. It is given again at three years and four months old as part of the 4-in-1 (DTaP/IPV) pre-school booster, and at 14 as part of the 3-in-1 (Td/IPV) teenage booster.

– Tell me more about polio

Most people who get polio do not have symptoms but some suffer mild, flu-like issues such as a high temperature, extreme tiredness, headaches, vomiting, a stiff neck and muscle pain.

In one in 100 to one in 1,000 infections, the polio virus attacks the nerves in the spine and base of the brain.

This can cause paralysis, usually in the legs, that develops over hours or days.

If the breathing muscles are affected, polio can be life-threatening.

The last case of natural polio infection acquired in the UK was in 1984.