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Home » First US polio case in a decade — what are the vaccine facts?

First US polio case in a decade — what are the vaccine facts?

New York health officials have discovered a polio case in an adult — it is the first case in the country since 2013. The good news is if you’re vaccinated, you probably don’t have to worry about it. The bad news is if you’re not, you are at risk of the deadly disease, so get vaccinated.

Now, there is a lot of bad information about this first polio case. Some people are claiming that a vaccine might have caused it, which is technically correct, but I’ll get into that later in this article. Some people are saying the polio vaccine isn’t effective, which is absolutely incorrect.

Let’s take a look at polio and this case in New York. You know, the facts.

All about polio and the polio vaccine

Polio, or poliomyelitis, is an infectious disease caused by one of three poliovirus serotypes: types 1, 2, and 3. Polioviruses are in the group of viruses called enteroviruses which usually infect the digestive tract. They are usually transmitted through the fecal-oral or oral-oral routes.

In about 0.5% of symptomatic cases, the virus moves from the intestinal tract to affect the central nervous system, and muscle weakness develops resulting in flaccid paralysis

This can develop over a few hours to a few days. The weakness most often involves the legs, but may less commonly involve the muscles of the head, neck, and diaphragm. Many people fully recover. In those with muscle weakness, about 2 – 5% of children and 15 – 30% of adults die.

There is no cure for polio; however, it is easily prevented with the polio vaccine, which is available in two forms. The first is the inactivated virus vaccine that is injected which is based on the original vaccine developed by Jonas Salk. This version is usually known as IPV or injectable polio vaccine.

The second version uses a live attenuated (weakened) virus given orally which was originally developed by Albert Sabin. This is generally known as OPV or oral polio vaccine. OPV has not been authorized for use in the USA since 2000.

The IPV vaccine is used throughout the developed world and is very effective in preventing polio. It also has an excellent safety profile. On the other hand, the OPV version is easier to give (no syringes and needles) and easier to transport, so it is used in developing countries and areas that have warmer climates.

Polio has more or less been eradicated across the world but maybe endemic in impoverished countries that have lower vaccination rates and lack clean water. Most cases remain in Afghanistan and Pakistanaccording to the Centers for Disease Control and Prevention.

Unfortunately, OPV has been linked to circulating vaccine-derived poliovirus (cVDPV), a very rare virus caused by the mutation or recombination of the attenuated viruses used in the oral polio vaccine. While cVDPVs are rare, cases have been increasing in recent years due to low immunization rates within certain communities. cVDPV type 2 (cVDPV2) is the most prevalent, with 959 cases occurring globally in 2020.

cVDPV does not generally infect individuals who have received the polio vaccine.

person holding injection
Photo by on

So what’s going on with the new US polio case?

The individual from Rockland County, NY likely contracted the virus from someone outside of the country who had taken an oral polio vaccine. The individual was not vaccinated against polio so they were susceptible to contracting cVDPV.

The majority of people in the United States have been vaccinated against polio — nearly 93% of children have by the age of two, the CDC says — because in many states children require a polio vaccine to attend school. However, some people are granted religious exemptions, and a handful of states leave that decision to the parents.

The 7% who are not vaccinated against polio are susceptible to cVDPV and may contract the disease, especially if they visit areas of the world where the oral vaccine is the preferred version of the polio vaccine.

The facts are:

  1. The infected person was not vaccinated.
  2. They contracted cVDPV from someone who had received OPV.
  3. They did not contract the disease from an American since most Americans have received the injected polio vaccine, which cannot develop cVDPV.

Should we be worried? No, unless you are not vaccinated against polio. Unfortunately, there are a lot of pockets of unvaccinated individuals. And some unvaccinated people may visit areas with endemic wild-type poliovirus and cVDPV.

Israel had an outbreak of cVDPV in early 2022. All of the cases occurred in unvaccinated or partially vaccinated individuals. Israel only recently stopped using OPV, so there was a greater risk of cVDPV.

In fact, the CDC states that before any international travel, those who are unvaccinated, incompletely vaccinated, or with an unknown polio vaccination status should complete the routine polio vaccine series. The CDC also recommends that before traveling to any high-risk destination, adults who previously completed the entire routine polio vaccine series receive a single, lifetime booster dose of polio vaccine.

The answer to all of your worries is to get the polio vaccine, preferably IPV. It’s safe. And it’s effective.

Michael Simpson

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