Chevron icon It indicates an expandable section or menu, or sometimes previous / next navigation options. HOMEPAGE

We're on the verge of eliminating one of the most tragic diseases in history

polio historic paralyzed
A physical therapist assists two polio-stricken children in this 1963 photo. CDC (PHIL) / Charles Farmer

In 1952, at the height of the polio epidemic, more than 20,000 Americans got polio. Many were left permanently paralyzed.

Advertisement

We've come a long way since then.

In 2015, there were only 96 cases of polio in the whole world, and the disease could be entirely gone within the next few years.

Up to this point, we've only ever completely eradicated one human disease: smallpox. The last case occurred in 1977. Guinea worm will likely be eradicated soon as well, since it only had 22 cases in 2015

This progress to combat polio is incredible, since as recently as 1988, 350,000 people had the debilitating disease, the majority of whom were children. 

Advertisement

The Global Polio Eradication Initiative — a partnership between the WHO, the CDC, UNICEF, and Rotary International — sums up the coordinated global effort behind this remarkable decline:

In 1988, when the [Initiative] began, polio paralysed more than 1000 children worldwide every day. Since then, more than 2.5 billion children have been immunized against polio thanks to the cooperation of more than 200 countries and 20 million volunteers, backed by an international investment of more than US$11 billion.

The World Health Organization estimates that 1.5 million children's lives have been saved and 13 million people are able to walk today because of the public health push to eradicate polio. 

Not gone yet

Polio is highly infectious. It's spread through human contact, usually through infected stool — a particularly dangerous route of transmission among children who are not yet potty-trained, as well as in areas with poor sanitation systems. People can also catch it by coming into contact with contaminated food or water.  

Advertisement

Afghanistan and Pakistan are the only two countries where polio is still spreading naturally. They were responsible for all 70 wild cases last year. 

Afghani child with Polio
Fawad Rahmani, 11, has had polio since he was 2 years old. He lives in Kabul, Afghanistan, one of the few countries where people are still fighting the disease. Getty Images/Paula Bronstein

The other 26 cases in 2015 were due to a very rare occurrence called "vaccine-derived poliovirus," according to the Global Polio Eradication Initiative.

When someone is immunized, they excrete some of the weakened virus that is used in the oral vaccine. In areas of poor sanitation, that weakened version of the virus can then spread further, providing what the WHO calls "passive immunization." But in severely under-immunized populations, that weakened virus can circulate for a year or more, giving it time to mutate and strengthen into a virus that can actually cause paralysis.

These cases are exceedingly rare; there were billions of doses of the oral polio vaccine distributed between 2000 and 2015 and fewer than 760 cases of vaccine-derived poliovirus. "The small risk ... pales in significance to the tremendous public health benefits associated with" the vaccine, WHO writes.

Advertisement
girl receives polio vaccine
A girl receives an oral polio vaccine. CDC Global/Flickr

Up to this point, we've relied on the oral vaccine because it's more effective at preventing the spread of polio from person-to-person, it's easier to administer, and it costs only 15 cents per dose (compared to $1 for the injected vaccine). 

But once no more wild cases are reported, health agencies around the world are going to switch over to the other kind of vaccine, which is injected and contains an inactivated form of the virus that can't mutate back to an infectious state. 

Even after no more polio cases of any kind are reported, health officials will have to keep vaccinating children and monitoring the world to make sure the disease stays gone. It took three years after the last case of smallpox before the WHO declared that disease eradicated in 1980. 

Peter Crowley, head of UNICEF's global efforts against polio, even told NPR in 2015 that the agency is "aiming to halt all transmission of wild polio virus next year."

Advertisement

That means there's a chance that this year could be the last that any child in the world gets polio, something that would be a major medical and humanitarian achievement.

Vaccines
Advertisement
Close icon Two crossed lines that form an 'X'. It indicates a way to close an interaction, or dismiss a notification.

Jump to

  1. Main content
  2. Search
  3. Account