Why has polio emerged in the US, UK and Israel? A polio eradication expert weighs in.

Oliver Rosenbauer: Well, they’re not exactly caused by the polio vaccine itself. What is happening is the oral polio vaccine that is being used — and that’s been used all over the world billions of times, and through which polio has been almost globally eradicated — it contains a live vaccine virus. It’s a weakened vaccine virus, but it’s live. So, what happens is that you give this vaccine to a child and that child develops immunity, and then the vaccine virus basically multiplies in that child’s gut and is actually excreted in the stool, just like a normal polio virus would. And it can actually spread to other children. In 99% of the cases, that’s actually a good thing, because you passively immunize other children that way. The problem is, if you allow this vaccine virus to continue to spread in the community and to continue to circulate, and if that happens, it can become, again, genetically changed from a weakened vaccine virus to a strong vaccine virus, able to cause paralysis. And that’s what is known as a vaccine-derived polio virus.

Well, I think we’re not just seeing these cases pop up now. We’ve been seeing them pop up throughout the use of this particular vaccine. It’s just that it’s popped up in a place like New York, which hasn’t had polio in a long, long time. The risk of these things emerging are very, very low. And the reason why we use this particular vaccine is that it has the ability to interrupt person-to-person spread. There’s another vaccine that is used. It’s called the inactivated polio vaccine — or the Salk vaccine, if you like — and it’s injected. It contains an inactivated polio vaccine and it offers excellent personal protection. But the drawback on that is [that] it offers very limited ability to be able to stop person-to-person spread of the virus, and in an eradication effort, that’s what we’re really after.

I would say the following: I think both the UK and the US did a fantastic job in identifying a public health risk. You know, there’s one case in New York, which is a paralytic case — one person paralyzed by the disease, which is tragic — but for the most part, the virus has been only isolated in sewage systems. So, the local authorities have identified this risk and are, right now, doing all the right things in addressing this public health risk. And the name of the game now is to make sure that you do not allow polio to reestablish a foothold in your community. And to do that, you make sure that your population is fully vaccinated.

We’re worried about any person who is not vaccinated against polio, because then that individual is not protected. And certainly the vaccine that’s being used in the United States, the inactivated polio vaccine, it’s one of the safest, if not the safest vaccine that is out there. It is a killed vaccine virus, so there is absolutely no chance of catching polio from it. There is no chance that you would see these vaccine-derived polio cases arise with inactivated polio vaccines. The only thing that it will do, is to protect you from lifelong paralysis. And, most of us have forgotten what polio actually is. It is a devastating, deadly disease. It is an extremely painful disease. And it is so easily preventable, and so, if it’s a matter of getting one injection in the arm, which is completely safe, and then be sure and be assured that you’re not going to catch this disease, I think it’s worth doing, definitely.