The global fight against polio — how far have we come?

Polio is an infectious disease that affects children in particularly terrible ways. Once the poliovirus invades the nervous system, it can cause irreversible paralysis in a matter of hours. As a consequence, many affected children suffered from permanent disability of the muscles in their legs. In the worst cases, it affects the muscles a child uses to breathe, which means that the child suffocates and dies.

To prevent them from dying of suffocation, polio victims were once placed into large mechanical breathing apparatuses called iron lungs. The iron lung was both a lifeline and a life sentence for those permanently paralyzed by the virus, as they would have to remain inside the metal box for years.

Children are still suffering from polio today, but the disease is much rarer than it once was. In this short article, I want to show how far the world has come in our battle against polio, and I want to show that we today have the opportunity to end polio once and for all. This — the global eradication of polio — would surely rank among humanity’s greatest achievements.

Just a generation ago, polio was spreading fear around the world

In the first half of the 20th century, many cities around the world suffered through horrible epidemics of polio. The disease can spread through contaminated food and water, especially in places with poor sanitation and hygiene. To turn the tide, scientists worked tirelessly on a vaccine.

It was Jonas Salk who developed the first successful polio vaccine — the inactivated poliovirus vaccine. The development of a working vaccine was announced on 12 April 1955. It was celebrated as “more than a scientific achievement,” according to Salk’s biographer Richard Carter.² “People observed moments of silence, rang bells, honked horns, blew factory whistles, fired salutes.” The vaccine “was a folk victory, an occasion for pride and jubilation.”

These celebrations were not misplaced. Another vaccine — the oral poliovirus vaccine — was developed by Albert Sabin soon afterward, and both vaccines made it possible to end the terrible epidemics of the past. By 1979, wild poliovirus was entirely eliminated from the US.³ Millions of children who would otherwise have been paralyzed instead lived healthy lives.

Although the oral poliovirus vaccine (OPV) was easy to provide at scale because it was given as liquid drops, it had the problem that the altered live poliovirus used within it could mutate and, in rare cases, could regain its ability to attack the central nervous system. Since 2020, the world has also had new effective vaccines called novel Oral Poliovirus Vaccines (nOPV), which can be used to prevent cases of vaccine-derived poliovirus.

The big chart shows how far the world has come in its fight against polio.⁴ As recently as the 1980s, hundreds of thousands of people worldwide became paralyzed by the virus every year. Since then, the efforts against polio have been successful in more and more regions of the world, and the spread of the virus has been contained greatly, as the chart shows.

This global reduction of paralytic polio cases is only part of the success. There were previously three different serotypes of wild poliovirus, and immunity to one serotype does not confer immunity to the others. Two of them were eradicated in the last decade:

• The last case of wild poliovirus serotype 2 was seen in 1999 in India. It was declared globally eradicated by the WHO in 2015.
• The last case of wild poliovirus serotype 3 was seen in 2012 in Nigeria and declared eradicated in 2019.

The maps below the chart show how polio was eliminated in more and more countries. Back in 1980, polio was still endemic in 147 countries around the world. By 2000, North and South America were certified to be polio-free. Twenty years later, most regions in the world are certified to be free of polio.

A global vaccination campaign made this success possible

The chart shows how this was possible.⁵ Back in 1980, only 1 out of 5 of the world’s infants got vaccinated. By now, that ratio has flipped, and 1 out of 5 are not vaccinated.

People around the world — all of us — contributed to this global success. First, by ensuring our children get vaccinated. And second, because much of the relevant work was paid for by public funds through our taxes.

For our generation today, polio eradication is within reach

The charts also show that during the COVID-19 pandemic, the vaccination rate against polio fell, and the number of cases increased.

But, despite the setback due to COVID, we are in a much better position than the generations before us. As we’ve seen in the three maps above, the disease has been eliminated from most countries in the world. The last remaining wild poliovirus is only prevalent in two countries. Today, our generation has the chance to achieve one of the most ambitious goals humanity can possibly set for itself, the global eradication of a disease.

We should not make the mistake of becoming complacent now that we’ve come so far. Going from low numbers to eradication is hard. It will depend on our efforts now to make this happen and eradicate polio once and for all.

But it is possible. The world has already eradicated one of the very worst human diseases: smallpox — a disease that is estimated to have killed at least half a billion people in the last 100 years of its existence — which was eradicated in 1980.⁶

We know what we need to end polio globally:

• Widespread access to the novel Oral Poliovirus Vaccines mentioned earlier, which don’t carry the same risk of rare vaccine-derived poliovirus infections.
• Access to clean water and sanitation facilities for everyone.
• And good data, as my colleagues Saloni Dattani and Fiona Spooner emphasized in their article on the importance of testing and data in the fight against polio. Only by testing widely can we make sure to detect every last case of polio so that we can protect those around them.

The data in this article have shown how very far we have come. Now, let’s bring this global project to an end and eradicate this disease for all children around the world and for all who come after us.

Max Roser (2024) - “The global fight against polio — how far have we come?” Published online at OurWorldInData.org. Retrieved from: 'https://ourworldindata.org/global-fight-polio' [Online Resource]

@article{owid-global-fight-polio,
    author = {Max Roser},
    title = {The global fight against polio — how far have we come?},
    journal = {Our World in Data},
    year = {2024},
    note = {https://ourworldindata.org/global-fight-polio}
}

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