The first case of polio since 2013 was reported in the US in Rockland County, NY. So far there are no other reported cases. Hopefully this is just an isolated case, but it highlights the fact that polio still exists in the world.

Poliomyelitis is an infection caused by the polio virus, which infect the anterior horn cells of the spinal cord. This causes severe paralysis. Prior to vaccination the disease paralyzed hundreds of thousands of children worldwide every year. After vaccines were introduced in the 1950s and 60s, cases plummeted, reduced by over 99%.

The CDC states that the US has been polio free since 1979. This is considered “elimination” – the disease is no longer endemic in the US. Since then there have been only a few isolated reported cases imported from outside the US, the last in 2013, and now another case.

In 2002 the WHO predicted they would be able to eradicate polio from the world by 2005. It is possible to eradicate polio because there is no non-human reservoir. This was accomplished through a robust vaccination campaign. However, as close as they came, their efforts were thwarted by conspiracy theories being spread in Nigeria, one of the last three countries with infections. An anti-vaccine campaign there allowed polio to spread.

It took 15 years to get back to that same point, being on the brink of eradication. By 2020 wild-type polio was eliminated from Africa, and existed only Pakistan and Afghanistan. Although there was an increase since 2016 in these last two countries, once again the WHO could see the finish line, and were making a final push to get enough people vaccinated to complete eradication. Then the COVID pandemic hit.

COVID caused a significant setback in the WHO’s efforts to eradicate polio. Poor countries, especially in Africa, had to suspend their vaccine programs. The WHO also had to divert resources to the pandemic, and the US was threatening to reduce WHO funding, including specifically for their vaccination program. Now, two years later, polio cases have been reported in eight African countries, and continue in Pakistan and Afghanistan.

As of 2022, cases of polio are increasing in Africa and remain in Pakistan and Afghanistan. We may have missed yet another chance to eradicate polio, and will have to spend years trying to get back to the brink of eradication.

Of note, there are essentially two sources of polio – there is the wildtype polio virus that is spreading through populations, and vaccine-derived polio. The latter occurs when people are vaccinated with the live attenuated vaccine (which is not used in the US, where the inactivated virus vaccine is used). Live weakened virus can spread through feces, and unvaccinated children can catch the vaccine-derived virus. So still the best way to prevent vaccine-derived cases is through vaccination (to eliminate vulnerable hosts).

The NY case is a vaccine-derived virus, and the man who contracted it was unvaccinated. The strain of the virus has been linked to a strain in Israel, but this strain has also been found in the UK, so it’s not clear where the subject contracted the virus from.

One way to track viral infections is to look for viral DNA in wastewater. In fact, polio virus has been found in the wastewater in New York, and also in London. There have been no further cases reported, but this means there are likely people shedding the virus through waste. This is highly concerning, and is something that needs to be further monitored.

And this is the problem – polio is highly contagious. The only proven way to prevent infection is with vaccination. The dramatic reduction in polio cases over the last 70 years has been entirely through polio vaccine programs, and the only way to eradicate polio is by making those programs as thorough as possible.

The recent case in NY also highlights the fact that we still need to vaccinate children against polio, even in countries where polio has been eliminated. Otherwise we risk new outbreaks in those countries, and eradication becomes an endless losing game of whack-a-mole. Essentially we need to vaccinate the world against polio until it is completely eradicated.

The recent rapid increase in polio and spread to previously polio-free countries shows how quickly the virus can bounce back. It also highlights the absurdity of the anti-vaccine movement, who have pushed back against the polio vaccine asking why Americans need to be vaccinated against polio when it is not spreading in the US. This is why.

The recent return of polio also highlights the importance of the WHO, who is heading the polio eradication effort. Even if there is legitimate criticism of the WHO, that does not mean it doesn’t provide some essential services. Reducing or cutting funding for the WHO would be a disaster, and would surrender any hope of eradicating polio.

Now is the time to increase our efforts to have a thorough polio vaccine program and finally eradicate this serious infection. We are still relatively close to this goal (historically speaking). All politics needs to be set aside and this needs to be a world-wide priority. We can only accomplish this together, because even a single holdout can mean failure.

Author

  • Founder and currently Executive Editor of Science-Based Medicine Steven Novella, MD is an academic clinical neurologist at the Yale University School of Medicine. He is also the host and producer of the popular weekly science podcast, The Skeptics’ Guide to the Universe, and the author of the NeuroLogicaBlog, a daily blog that covers news and issues in neuroscience, but also general science, scientific skepticism, philosophy of science, critical thinking, and the intersection of science with the media and society. Dr. Novella also has produced two courses with The Great Courses, and published a book on critical thinking - also called The Skeptics Guide to the Universe.

Posted by Steven Novella

Founder and currently Executive Editor of Science-Based Medicine Steven Novella, MD is an academic clinical neurologist at the Yale University School of Medicine. He is also the host and producer of the popular weekly science podcast, The Skeptics’ Guide to the Universe, and the author of the NeuroLogicaBlog, a daily blog that covers news and issues in neuroscience, but also general science, scientific skepticism, philosophy of science, critical thinking, and the intersection of science with the media and society. Dr. Novella also has produced two courses with The Great Courses, and published a book on critical thinking - also called The Skeptics Guide to the Universe.