Dr. Kohli Talks Polio

By Payal Kohli, MD, FACC - Last Updated: September 13, 2022

Polio, a virus that was once nearly eradicated, reared its head back in June when it was detected in an unvaccinated New York State resident and subsequently in New York wastewater; spurring concerns that the virus, which at its peak in 1952 killed 3,000 people, may spread again throughout the nation.

DocWire News Medical Lead Payal Kohli, MD, FACC, spoke about the resurgence of polio, and the importance of getting vaccinated against it.

DocWire News: Talk to us about polio – how is it characterized, and how is it transmitted?

Dr. Payal Kohli: Polio is a virus, and the virus has been gone for a long time. As a physician, in fact, it’s funny because I have never actually treated polio in my entire career. But essentially what it is, is a virus that lives in the throat, in the intestines, and it can be transmitted from person to person through human-to-human contact. So it can be spread through a sneeze or a cough because those are respiratory droplets that carry the virus, but it can also be spread through the fecal oral route. What that means is if you come into contact with contaminated waste water and happen to touch your mouth or your nose, because you actually shed it in your stool if you’re infected with polio. Now, the interesting thing about polio is that only one out of four people with active polio actually have symptoms during the initial infection. So the majority of people, three out of four, don’t know that they’re symptomatic and they could actually be shedding the infection without realizing it.

What impact did polio have prior to the development of a vaccine? 

I mean, it was devastating. It was one of the most devastating conditions around, and I think we all remember FDR who contracted polio in his thirties and was basically wheelchair bound for most of his adult life. And Even though the complications of meningitis and paralysis and post-polio syndrome are relatively rare, they’re not all that uncommon, and one out of 100 or one out of 200 people can develop these life-threatening complications. Once they have them, there’s no treatment, there’s no way to get them better. So that’s where the advent of the vaccines really sort of changed the landscape of polio, especially in the developing world where we would often see kids and young adults and adults kind of really crippled by these post-polio complications with very little access to medical care to help support them through it.

Why are we now seeing more and more cases of polio in the U.S.?

Well, I think there’s a couple of reasons for why we’re now seeing polio in the waste water. The first is that we have more people that are not fully vaccinated. There has been vaccine apathy. There’s been vaccine misinformation with concern for autism and such, so many people are now not vaccinating their children, not getting vaccinated themselves, which can obviously facilitate the transmission of this infection. It was eradicated in the United States in 1979, and it’s now made a resurgence or a comeback. The second is that some experts actually say, we may have had this for a little bit of time and really only started picking it up now because some of the routine waste water surveillance was a little bit suspended during the COVID-19 pandemic, and we weren’t doing nearly as much as we should have.

The reason for that is because here in the United States we have largely used the inactivated vaccine, which, as you know, is inactivated. It’s a shot and so it induces antibody immunity, but it doesn’t actually induce immunity in your intestines where polio can live. And so you could still potentially not get sick with polio, but contract it, be shedding it in your intestines and your waste water because you’ve been vaccinated with that vaccine, as opposed to the oral polio vaccine, which is used in much of the developing world where you actually get a little bit in your mouth. And so because it goes into your mouth and then into your intestines subsequently, you actually do develop mucosal immunity, which means that you have antibodies in the intestines themselves, and so you’re less likely to shed it in the waste water. So, I believe it’s probably a combination of both factors and the fact that our surveillance has now picked up again that we’re now seeing it, but certainly very concerning to see a disease that was eradicated here now having a resurgence.

In the U.S., we use the inactivated polio vaccine whereas some other countries use the live-attenuated oral polio vaccine. Why is that?

I’ll say one more thing about the vaccine. One of the reasons that we’re using the inactivated vaccine here in the US, as opposed to the oral vaccine, is because there’s a rare, like one in two million chance, that the oral vaccine can actually give you paralysis. Because, remember, it’s a live attenuated vaccine. Vaccine-associated polio, which has been reported in the developing world, occurs at that rate at about one in two million and then, of course, can be devastating to get it from the vaccine. So that’s one of the reasons the CDC and public health organizations have really made an active decision to use the inactivated vaccine. Now, you can imagine access-wise, the oral vaccine is much easier in the developing world. And because it does induce that intestinal immunity, some people suggest that it actually has a broader type of antibody response that it elicits.

Did the COVID-19 pandemic impact polio vaccination rates?

I think in many different ways, just like with a lot of the other vaccines that we’re seeing, it’s really limited our ability to access these vaccines, one, because people had corona phobia, so a lot of people were not getting their routine medical care, and that includes a lot of routine childhood care. Even adults, for that matter, who maybe weren’t fully vaccinated as children because they emigrated from another country or what have you, may not necessarily have had their polio titers checked. So I think one part of it was access, willingness to get vaccines and just sort of general avoidance of medical care that has had an impact.

But another part of it, I think is a bigger problem, which is reflected in our infrastructure, the ability to manufacture, the ability to do lab tests to confirm titers. All of those were compromised during the COVID-19 pandemic, and I think that that may have led to a drop off, not just in the polio vaccine, but others as well, just in vaccination rates and a lot of preventive care worldwide.

What advice would you offer health care providers and patients alike to mitigate the spread of polio?

Get vaccinated, get vaccinated, get vaccinated because we have a vaccine that works. We have a vaccine that’s highly effective. In fact, if you’ve gotten all four doses as a kid or three doses as an adult, you have a 99% efficacy for prevention of infection. And, of course, we know that vaccinated people are also less likely to transmit the infection. One of the best tools that we have and what we’ve learned from this pandemic is really that vaccines are empowering. Without the vaccine, our life was shut down with COVID, and now with the vaccine, we really have been able to get things back to normal. With polio, it’s very much the same. We do not want to wake up a disease that’s sleeping that has devastating consequences with chronic illness and death in some, with no known treatment. So we have kind of science has opened the door for us to prevent this illness. All we have to do is just walk through it.

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