On 24th October 2023 global health leaders, advocates, and communities highlight efforts to end poliomyelitis (polio). Each year World Polio Day is observed to “raise awareness of the importance of polio vaccination” as protection from the disease, and to “celebrate the many parents, professionals, and volunteers whose contributions make polio eradication achievable”.
“To ensure a polio-free future for everyone, efforts must continue to maintain high immunisation coverage, implement high-quality surveillance to detect any presence of the virus, and prepare to respond in the event of an outbreak.”
The “Make Polio History” campaign is supported by participants in over 30 countries in every region with calls for partners, donors, and governments to pursue eradication goals.
A prehistoric history
The World Health Assembly committed to the eradication of polio in 1988, and although significant progress has been made, the disease continues to cause suffering. WHO states that polio, caused by the poliovirus, has “existed since prehistoric times”. However, the first known clinical description was not until 1789 by British doctor Michael Underwood. It was formally recognised as a condition by German physician Jakob Heine.
Throughout the 19th and 20th centuries, “frequent” epidemics allowed polio to become “the most feared disease in the world”. The worst recorded US outbreak in 1952 killed over 3000 people. Death is not the only consequence; survivors experience “lifelong” effects such as deformed limbs or dependence on breathing devices like the iron lung. Polio took hold of the world, killing or paralysing “over half a million people every year”.
“With no cure, and epidemics on the rise, there was an urgent need for a vaccine.”
Vaccine development
A “breakthrough” was secured in 1949, as John Enders, Thomas Weller, and Federick Robbins of Boston Children’s Hospital were able to successfully cultivate poliovirus in human tissue. Their work was awarded the Nobel Prize in 1954. Shortly after this achievement, the first successful vaccine was developed by US physician Jonas Salk, who used killed virus to vaccinate himself and his family in 1953.
In 1955 the results of an investigation vaccinating 1.6 million children were published and the inactivated polio vaccine (IPV) was licensed. Despite the success of this vaccine, Salk decided not to profit from sharing the formulation or production processes, suggesting in a 1955 interview that “the people” owned the patent for IPV.
Another polio vaccine, the oral polio vaccine (OPV), was developed by Polish American physician and microbiologist Albert Sabin. This vaccine was live-attenuated and could be delivered as drops or on a sugar cube. Interest from the US at this point was “low” as the Salk vaccine was “in wide use”. Hilary Koprowski carried out the first test of a live-attenuated vaccine on humans in 1950, with further trials taking place.
Immunisation programmes
The oral vaccine was an “ideal candidate” for mass vaccination campaigns with Czechoslovakia adopting it in early 1960; it was the first country in the world to eliminate polio. Alongside the ease of administration, OPV had a “benefit that paved the road to eradication”. It interrupted the chain of transmission, preventing the spread of the virus.
In 1979 Rotary International began a multi-year project to immunise 6 million children in the Philippines. In 1988, the World Health Assembly passed a resolution to eradicate polio and the Global Polio Eradication Initiative (GPEI) was launched. In 1994 polio was eliminated from the Americas, with the Western Pacific following in 2000. From the turn of the century cases have been reduced by “more than 99% worldwide”. By July 2021 only 2 countries recorded cases of wild poliovirus: Afghanistan and Pakistan.
Does the vaccine compromise eradication?
Although OPV is a hugely successful vaccine, WHO acknowledges that it comes with a “disadvantage”. Where vaccination coverage is lower than desired, the weakened vaccine virus can begin to circulate in undervaccinated communities. If it circulates long enough it can “genetically revert” to a ‘strong’ virus, resulting in circulating vaccine-derived polioviruses (cVDPVs). However, in areas that have adequate coverage the risk is reduced.
Putting polio in the past
The Global Polio Eradication Initiative (GPEI) claims to have both the “knowledge and tools” to end polio but demands support to add polio eradication the “list” of “wins for humanity”.
“Today, there are proven strategies and new tools to deliver vaccines in the highest-risk areas for polio, which are also some of the world’s most challenging and hard-to-reach settings. Promising trends in polio-affected countries that have been seen in other places now polio-free suggest that today, the virus is truly on its last leg.”
GPEI suggests that “attention and support” will bring polio eradication within reach.
“It will take all of us, but together, we can make history again and end polio for good.”
Here at The World Vaccine Congress polio has been a subject of interest at many events. Recently in Barcelona we heard from Dr Ajoy Chakrabarti on a “portfolio of vaccines to enable Polio eradication”. We look forward to future discussions as polio eradication becomes a reality; don’t forget to subscribe for more insights.
