You’ve heard about measles, you’ve probably even heard about smallpox… but what do you know about polio?

Feeling feverish? It could be the outcome of a fevered excitement to read this article, or it could be polio.
Polio, also known as poliomyelitis (let’s stick with polio), is a highly contagious illness that can, along with fever, induce a paralytic state – one could say it freezes lungs in their tracks. It’s caused by poliovirus, which before vaccines were available was free to have its way with the general populace, particularly during the tail-end of WWII. As is often the case, woes bred woes and with a general decrease in hygiene accompanying an increase in crowding, polio caused many deaths – particularly amongst young children.

Children in an “iron lung” after suffering from polio induced paralysis of the lungs.
https://rarehistoricalphotos.com/children-iron-lung-advent-polio-vaccination-1950/

Fortunately, an effective vaccine was created and in this modern age polio is almost eradicated, with the very illness becoming somewhat of an “ailment of old times”. Less fortunately, there’s been a slight issue with vaccinations…

In essence, the vaccine is causing polio.

Obviously, that’s not ideal.
However, before sharpening any “anti-vaccination” pitchforks, allow me to slip into a little first person prose (the benefits of a blog).

Our fast-paced, high-tech life can make it hard to navigate and sift fact from fiction. The constant plying of information can be overwhelming, with many sources having an agenda of persuasion. For example some sites may simply state “the vaccine is causing polio”, and that could quite understandably leave you with feelings of concern or trepidation when considering whether or not to vaccinate your children.
I would much rather provide you with a summation of information and allow you, the reader, to form your own opinion.

So, if you please, read on for an explanation.

The vaccine is not causing any immunised individuals to develop polio. What’s happening is that in 1988 the W.H.O. (World Health Organisation) made a plan, a very ambitious plan of globally eradicating polio. One challenging part of this was that even remote, impoverished areas needed to be reached – a tough call when staffing and sanitation levels were dubious. The only practical way to implement vaccination in these areas was through use of an oral vaccine – drops taken by mouth.

Within this liquid are a combination of attenuated poliovirus: Type I, II & III. They are called attenuated because their genetic make-up has been altered to the point where they are no longer considered virulent/are not capable of causing polio. However, they are still live viruses, and will for a short time be present in the newly immunised person’s stools. In situations where there is a public sewerage system and good hygiene practices this wouldn’t be an issue, but for some isolated areas this isn’t the case so coupled with many individuals not getting the vaccine, we end up with transmission. As this cycle repeats itself, the attenuated strands are undergoing mutations and eventually we see a reversion to virulence. These variants are referred to as cVDPVs (a mouthful of “circulating vaccine derived polio virus”). Now, any cVDPV infected individuals are at risk of developing polio.

This means that it’s still the unimmunised that are at risk, but that the vaccine is responsible for exposing these unimmunised individuals to the virus. There are a few ways to work around this, one being more thorough immunisation of these remote regions. Another way, and this is the area that my next post focuses on, is identifying how this virulence is regained.

In the mean-time feel free to peruse the following sites for more information on polio, both the illness and the virus.

https://www.medicalnewstoday.com/articles/155580.php
https://www.historyofvaccines.org/timeline#EVT_100314

Update – Following article can be found here: https://thismicrobiallife.wordpress.com/2019/09/13/to-be-or-not-to-be-the-question-of-virulence-as-posed-by-polio/