Polio in New York – An Infectious Disease Doctor Explains This Exceedingly Rare Occurrence

Jonah here. The discovery of a case of polio in New York has led to fears of a possible surge in the virus. In this piece from The Conversation, an infectious disease expert explains how the patient could have contracted the virus (from an oral vaccine), and where the campaign to eradicate polio stands today.

The first case of polio in the U.S. since 2013 was announced by New York state health officials on July 21, 2022. The U.S. resident had not been vaccinated.

Polio was a common cause of paralysis in children before safe and effective vaccines were invented in the mid-20th century. Thanks to global vaccination campaigns, polio is now almost eradicated, with only 13 cases of endemic wild poliovirus reported in 2022 to date worldwide.

The New York patient reportedly contracted a form of polio that can be traced back to the live, but weakened, poliovirus used in the oral polio vaccine. This version of the vaccine has not been used in the U.S. since 2000. Health officials said the virus affecting the male patient, who has muscle weakness and paralysis, likely originated somewhere overseas, where oral vaccines are still administered.

William Petri is an infectious disease specialist and chair of the World Health Organization’s Polio Research Committee. Here he explains what vaccine-derived poliovirus is and why the inactivated polio vaccine administered in the U.S. today can’t cause it.

What Are the Two kinds of Polio Vaccine?

Vaccines introduce a harmless version of a pathogen to your body. The idea is that they train your immune system to fight off the real germ if you ever encounter it.

The oral polio vaccine, originally developed by Albert Sabin, uses a live but weakened poliovirus that one swallows in a sugar cube or droplet. Scientists weaken – or attenuate – the virus so it can no longer cause disease.

The other kind of polio vaccine was originally developed by Jonas Salk. It contains inactivated, dead virus. It is administered by an injection.

In the U.S., children receive the inactivated polio vaccine at 2, 4 and 6 months of age. It provides nearly complete protection from paralytic polio.

How Can the Live Vaccine Lead to a Case of Polio?

The weakened form of the live virus in the oral vaccine cannot cause disease. However, because the vaccine is given orally, the weakened virus is excreted in the feces and can spread from someone who is vaccinated to their close contacts. If the weakened virus circulates person to person for long enough, it can mutate and regain its ability to cause paralysis.

The mutated virus can then infect people in communities with poor sanitation and low vaccination rates, causing disease and even paralysis.

This is an exceedingly rare occurrence. With more than 10 billion doses of the oral polio vaccine administered since 2000, there have been fewer than 800 cases of vaccine-derived polio reported.

Apparently, the current patient in New York was somehow exposed to a mutated poliovirus that had been transmitted after vaccination overseas. Earlier this summer, routine surveillance spotted vaccine-derived poliovirus in London’s sewage system, but no cases have been reported there.

Why Use the Oral Vaccine Anywhere if It Comes with this Risk?

There’s a positive aspect to the fact that the weakened live virus can circulate in the community once oral vaccine recipients shed it in their feces. Traveling a feces-to-oral route, it can help induce immunity even in people who weren’t directly vaccinated. The oral polio vaccine is also cheaper and easier to administer than inactivated polio vaccines.

Most importantly, the live-virus vaccine stops transmission of wild poliovirus in a way that the inactivated-virus vaccine does not. The eradication of polio in the Americas, Europe and Africa has been accomplished solely through the use of the live oral vaccine. Once polio has been wiped from a continent, then it is safe to stop using the oral live vaccine and use only the inactivated vaccine, which does prevent disease in recipients and does not pose the rare risk of vaccine-derived paralytic polio.

A new and safer oral polio vaccine that has been engineered not to mutate is now replacing the earlier live-virus vaccine. Thus, even this extremely rare complication of polio vaccination should soon become a thing of the past.

How Close Is the World to Eradicating Polio?

Thanks to tremendous global effort, two of the three viruses that cause polio have been eradicated. The world is now on the verge of eradicating the final one, wild poliovirus 1 (WPV1).

Today endemic polio is found only in Pakistan, with 12 cases of paralytic polio so far in 2022, and Afghanistan, with just one case this year. Africa has two cases, imported from overseas, which are being contained by additional vaccination campaigns.

Once wild poliovirus has been eradicated from the planet, vaccination efforts may be able to switch to the inactivated polio vaccine, eliminating the risk of any future vaccine-derived cases.

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  1. Tom Stone

    It’s hard to express how important the oral vaccine was to someone who grew up since polio’s near eradication.
    It was a Miracle.
    FDR’s case was the best known, but there were many and ending up in an iron lung was a real possibility if your family had money.
    If you were poor you died, as usual.
    I was in grade school when I lined up with all the other kids and got my sugar cube with the purple dot ( It’s not hard to get kids or horses to eat a sugar cube), too young to really understand what was going on, but I do remember my Mother’s reaction of wonder and joy.
    She was running the lab at Highland Hospital about that time and I remember watching her mix reagents while talking to a co worker about the end of Polio and how extraordinary it was.
    Now we have Wolensky.

    1. Raymond Sim

      We’ve got Walensky, and we’ve also got SARS-2 possibly nudging R0 up for a number of pathogens, and vaccine-strain polio circulating in places where it doesn’t look like getting stomped out any time soon.

      The second shot turning out to be a sugar cube was just amazing. It’s petty of me, but I take it personally that the eradication of wild-type polio is ballyhooed while vaccine-strain polio looks likely to continue causing disease for the foreseeable future, because it taints my happy memory.

    2. Imaginary solution

      A number of vaccines have been near-miraculous. My mother recounted to me that one of her classmates died of tetanus. By the time I was growing up, kids were vaccinated.

  2. Hickory

    I’m really trying to keep an open mind, having first paid attention to vaccines with these Covid vaccines rather than in earlier times. I’m in my mid-30s. The polio vaccine really sounds like an amazing accomplishment, and yet I keep noticing hubris that makes me skeptical:

    A new and safer oral polio vaccine that has been engineered not to mutate

    Do tell how is that possible? That seems like a very strong claim, and coming from the same establishment that I trust so little after the covid vaccination issues the past few years.

    I’m concerned about the monkeypox vaccination, not because I know anything about it but just ‘cause I distrust the system promoting it. I’m hoping a group like the flccc forms for monkeypox that finds non-vax treatments while I watch and see how well the monkeypox vax does. I know it’s a smallpox vaccine, but I still don’t feel like rushing out and getting it when it becomes available.

    Any info from other commenters on these points is welcome!

  3. Raymond Sim

    As usual, I appeal to the brain trust to set me straight if I’m wrong, but isn’t vaccine-strain polio still causing paralytic disease in Africa?

    It would be a great thing to be wrong about. Otherwise Dr. Petri’s remarks, as presented by The Conversation at any rate, strike me as the sort of mealy-mouthed stuff I’ve sadly come to expect from ID specialists who get quoted in media.

  4. Matthew G. Saroff

    A note on the guy who caught polio.

    He is described as an Ultra-Orthodox (Haredi) Jew who traveled to Poland and Hungary.

    This when juxtaposed with the opposition of Satmar Hassids to vaccinations, for reasons that I have never been able to find in Talmud, makes it almost certain that he is Satmar.

    1. Raymond Sim

      Hoo boy. I guess this is one of those ‘not suprising, but still shocking’ moments. I guess we’re going to find out what vaccine-strain polio can accomplish with a running start.

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