Poliomyelitis is caused by infection with poliovirus, which is usually spread from person to person, particularly in conditions of poor hygiene. According to the NHS:
“About 95% of people with polio won’t have any symptoms and will fight off the infection without even realising they were infected.”
“In less than 1% of cases, 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. The paralysis isn’t usually permanent, and movement will often slowly return over the next few weeks and months. However, some people are left with persistent problems and if the breathing muscles are affected, it can be life-threatening.”
In 2014 the NHS describes polio as a disease of the past and said that the last case of natural infection in the UK happened in 1984. The few cases since then where either brought in from other countries or caused by the live oral vaccine.  (HPA data shows no cases acquired overseas between 1994 and 2003, so all were acquired from the vaccine in this time period. )
Since 2004 the UK uses the inactivated polio vaccine. This is just as well, as there have been plenty of documented cases internationally, where polio outbreaks occurred immediately after mass-vaccination campaigns with the live vaccine (see for example ), leading researchers to wonder why these had happened despite the vaccinations but logically they must have happened because of them. The 1988 Oman outbreak is often cited, where most children had received at least 3 doses of the vaccine and where areas with high vaccination coverage had the highest attack rate and vice versa.  A similar vaccine-caused outbreak didn’t happen here in the UK. Better living conditions are a reasonable explanation.
The inactivated version now in use in the UK cannot cause the disease but the live oral vaccine is still being used for large-scale vaccination campaigns in countries like India, where cases of polio are said to have dramatically fallen, while authorities record an equally dramatic rise in acute flaccid paralysis , meaning people are still getting paralysed, but apparently not from polio.
The World Health Organisations says on its website: “Polio cases have decreased by over 99% since 1988, from an estimated 350,000 cases then, to 37 reported cases in 2016.”  These are worldwide figures, which is why Polio can be considered eradicated for all practical purposes. In the UK polio cases still get notified on occasions. In the past two decades these amounted to at most one per year  and even those don’t have to get laboratory confirmed before getting reported.
Unlike other diseases, polio did not go through a long decline before vaccinations started. Polio was only recognised as a separate disease in England in 1911 and saw a huge increase in the 1940s-1960s before disappearing again. Vaccines were introduced in the UK 1956 and 1962.
Why the disease spiked in the 1940s and 1950s is not known. A fact also not widely known is that the diagnostic parameters for Polio were radically changed at the time the vaccine was first introduced in the US. This re-definition alone caused most Polio cases to be removed from the statistics and the vaccine was credited with the improvement. This, at least, is what can be read in an issue of the Illinois Medical Journal of 1960 . So when looking at the above graphs, it appears polio disappeared thanks to the vaccine but let’s look at this article from 1960 in a bit more detail. In this scientific panel discussion various experts stated:
“In the fall of 1955 Dr Langmuir had predicted that by 1957 there would be less than 100 cases of paralytic polio in the United States. As you know, four years and 300 million doses of Salk vaccine later, we had in 1959 approximately 6000 cases of paralytic polio, 1000 of which were in person who had received three, four and more shots of Salk vaccine.”
“For every one case of known paralytic polio we have about 1000 cases of subclinical polio infections.”
“Prior to 1954 any physician who reported paralytic poliomyelitis was doing his patient a service by way of subsidizing the cost of hospitalization…The criterion of diagnosis at the time [was] … partial or complete paralysis…detected on two examinations at least 24 hours apart. … In 1955 the criteria were changed…unless there is residual involvement at least 60 days after onset, a case of poliomyelitis is not considered paralytic. Furthermore diagnostic procedures have continued to be refined. Coxasckie virus infections and aseptic meningitis have been distinguished from paralytic poliomyelitis. Prior to 1954 large numbers of these cases undoubtedly were mislabelled as paralytic poliomyelitis. Thus simply by changing the diagnostic criteria, the number of paralytic cases was predetermined to decrease in 1955 – 1957, whether or not any vaccine was used.”
Parents making their vaccination decision should consider the almost non-existent risk from polio in the UK. Vaccines used in the UK against Polio are: Pediacel, Infanrix-IPV, Repevax, Revaxis and Infanrix Hexa.Parents making their vaccination decision should consider the almost non-existent risk from polio in the UK.
- NHS website accessed March 2014
- Protecting the health of the Nation’s children: the benefit of vaccines – Health Protection Agency
- Lancet. 1991 Sep 21;338(8769):715-20
- The Hindu website
- The Present Status of Polio Vaccines, Illinois Medical Journal, August 1960 (PDF download)
- NHS website accessed May 2017
- World Health Organisation website accessed May 2017
- UK Notifications of notifiable diseases