The following essay is covered in The Conversation, an online publication.

New York state health officials announced the first case of the disease in the U.S. The US resident didn't have a vaccine.

Before safe and effective vaccines were invented, there were many cases of children being paralyzed by the disease. With the help of global vaccination campaigns, there are only 13 cases of endemic wild polioviruses reported to date worldwide.


The New York patient contracted a form of the disease that can be traced back to the vaccine. The vaccine hasn't been used in the US since 2000. According to health officials, the virus affecting the male patient, who has muscle weakness and paralysis, probably originated overseas, where oral vaccines are still administered.

The chair of the World Health Organization'spolio research committee is William Petri. He explains what vaccine-derived polioviruses are and why they can't cause it.

There are two types of vaccine for the disease.

A vaccine can cause a harmless version of a pathogen. If you ever come across a real germ, they will teach your immune system to fight it.

The oral vaccine uses a live but weakened version of the polioviruses that one swallows in a sugar cube or droplets. The virus can't cause disease if scientists weaken it.


The other type of vaccine was developed by the same man. There is a dead virus contained in it. An injection is used to administer it.

At 2, 4 and 6 months of age, children in the U.S. are given the inactivated vaccine to fight the disease. It provides complete protection from the disease.

The live vaccine can cause a case of the disease.

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The weakened form of the live viruses can't cause disease. Because the vaccine is given oral, the weakened virus can be passed on from person to person. The weakened virus can cause paralysis if it is allowed to circulate for long enough.

Poor Sanitation and low vaccinations can cause disease and even paralysis in people.


It's an extremely rare occurrence. Since 2000, there have been more than 10 billion doses of the oral vaccine given.

The current patient in New York is believed to have been exposed to a variant of the vaccine. There have been no reported cases of vaccine-derivedpoliviruses in London.

If the vaccine comes with this risk, why use it?

The weakened live virus can be spread in the community when oral vaccine recipients excrete it. Traveling a feces-to-oral route can help induce immunity in people who didn't get a vaccine. The oral vaccine is more convenient to administer.

The live-viruses vaccine stops the transmission of wildviruses in a way that the in-viruses vaccine doesn't. The live oral vaccine has been used in the eradication of the disease. It is safe to stop using the oral live vaccine and only use the inactivated vaccine once the disease has been eradicated from the planet.


The oral vaccine that has been engineered not to change is now replacing the live vaccine. It should soon be a thing of the past that there is a rare side effect of the vaccine.

How close are the world's to eradicate the disease?

Two of the three viruses that cause the disease have been eradicated thanks to the global effort. The world is on the verge of ridding itself of the last wild version of the disease.

Pakistan and Afghanistan are the only places in the world where the disease is endemic. Africa has two cases imported from overseas.

Eliminating the risk of future vaccine-derived cases is one of the goals of the eradication of wild polioviruses.


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