Nigerian family on a motorcycle receiving the polio vaccine. By Lisa K. Esapa.
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Polio, or poliomyelitis, is a crippling and potentially deadly infectious disease caused by a virus that spreads from person to person invading the brain and spinal cord which can lead to paralysis. 1 in 200 infections leads to irreversible paralysis. Of those paralyzed, 5% to 10% die when their breathing muscles become immobilized. Additionally, even children who seem to fully recover can develop new muscle pain, weakness, or paralysis as adults, 15 to 40 years later. This is called post-polio syndrome.

There is no cure, but there are safe and effective vaccines to prevent polio infection. Polio vaccine protects children by preparing their bodies to fight the polio virus. Almost all children (99%) who get all the recommended doses of vaccine will be protected from polio. Therefore, the strategy to eradicate polio is based on prevention by immunizing every child to stop transmission and ultimately make the world polio-free.

What is the global impact of polio?

  • Since 1988, more than 18 million people can walk today who would otherwise have been paralyzed, and 1.5 million childhood deaths have been averted thanks to the polio vaccine.
  • Four regions of the world are certified polio free—the Americas, Europe, South East Asia and the Western Pacific.
  • In August 2019, Nigeria marked three years without wild polio, opening the door for certification of the WHO AFRO region.
  • In October 2019, the certification of eradication of the type-three wild poliovirus (WPV3) signifies that the world has wiped out two (WPV2 AND WPV3) of the three wild polio strains—leaving just one more (WPV1) to go.
  • In 2019, cases of wild polio have increased relative to 2018, and outbreaks of vaccine-derived polio continue to spread across parts of Africa and Asia.
  • If a population is seriously under-immunized, vaccine-derived poliovirus can begin to circulate in a community. Circulating vaccine-derived polioviruses (cVDPVs) are extremely rare forms of poliovirus, which has circulated for a prolonged period of time uninterrupted and can mutate over the course of 12-18 months.

Who is at risk?

  • When you look at where wild polio cases or vaccine-derived poliovirus cases are arising today, they are all in places of unrest and with varying complex scenarios or limited access – Somalia, DRC, Lake Chad region, Syria, Pakistan, and Afghanistan.
  • Most people who get infected with poliovirus (about 72 out of 100) will not have any visible symptoms. Poliovirus is highly contagious, and people who don’t have symptoms can still pass the virus to others and make them sick.
  • About 1 in 4 people infected with poliovirus will experience flu-like symptoms, such as sore throat, fever, tiredness, nausea, headache, and stomach pain.
  • A smaller proportion of people with poliovirus infection will develop other more serious symptoms that affect the brain and spinal cord, such as paresthesia (feeling “pins and needles” in the legs), meningitis, and paralysis.
  • Polio anywhere is a risk to people everywhere. All countries will be at risk of polio importation until it is eradicated globally by preventing infection through vaccination.

What is CDC doing?

  • CDC and its international partners have made significant progress over the past 26 years. Through the Global Polio Eradication Initiative, CDC:
    • Works jointly with WHO and national Ministries of Health to plan and monitor polio’s spread and immunization activities in multiple countries worldwide
    • Evaluates risk and conducts assessments with GPEI partners for the Independent Monitoring Board, which meets quarterly to review performance of at-risk countries towards achieving polio eradication milestones
    • Promotes innovation and conducts research to improve immunization against polio and means to detect polio cases
    • Supports all 145 member labs in the Global Polio Laboratory Network with critical diagnostic services and genomic sequencing of polioviruses to help guide disease control efforts in many countries
    • Performs applied research for supplemental immunization activities
    • Deploys personnel and resources to support country eradication efforts
    • Trains and deploys international consultants to WHO and UNICEF through the Stop Transmission of Polio (STOP) Program

CDC is working to help stop this crippling disease forever and ensure the lessons learned and polio infrastructure continue to pay dividends to keep Americans safe and save lives around the world. For example, polio infrastructure supports health priorities beyond polio, including in these recent emergency response efforts: Ebola, cholera, measles, Marburg virus and Yellow Fever.

CDC scientist handling polio samples in a lab

Checking the finger marking of a nomadic child in Pakistan

Thanks to the tremendous efforts of health workers around the world, governments, and the partners of Global Polio Eradication Initiative (GPEI), polio cases have been reduced by 99.9% since 1988. However, we have seen an increase in the number of wild poliovirus cases this year in the two remaining endemic countries – Afghanistan and Pakistan. Additionally, between Jan 2019 and as of Nov 1, 2019, globally there were 117 cases of circulating- vaccine derived polio cases in fifteen countries (Angola, Benin, Central African Republic, Chad, China, DRC, Ethiopia, Ghana, Myanmar, Niger, Nigeria, Pakistan, Somalia, Togo and Zambia). Vaccine-derived polio is extremely rare and only happens in communities where immunity levels are low. Since the eradication effort began in 1988, an estimated 18 million cases of paralytic polio have been prevented while just over 1,000 cVDPV cases have ever been detected globally.

Stopping outbreaks and limiting the risk of circulating vaccine-derived poliovirus (cVDPV) emergence requires increasing assistance to cVDPV type 2 outbreak countries; using a novel, stabilized OPV2 in future; maintaining high population immunity in all countries; and ending all OPV use after certification of polio eradication. To address current cVDPV2 outbreaks, the CDC Polio Response is working to scale up and place additional technical experts for initial deployments in countries with active outbreaks to provide technical support.

Learn More:

Polio – CDC in the News

“While we have outbreaks of circulating vaccine-derived poliovirus Type 2, (cVDPV2) at higher levels than we anticipated, the numbers are still quite low compared to the amount of paralysis that has been prevented through the Global Polio Eradication Initiative. In fact, we’ve seen the aversion of 18 million paralytic cases of polio. That’s 18 million kids that would have otherwise been paralyzed by polio that were not.”
–John Vertefeuille, chief of CDC’s polio eradication branch, on CSIS’s Take as Directed Podcast

NPR: Polio Is Making A Comeback – November 15, 2019
“Because of the rising number of individual outbreaks, the CDC has taken a decision to do a surge staffing effort focusing on Africa.”
–John Vertefeuille, chief of CDC’s polio eradication branch

Scientific American: Two Strains of Polio Down, One to Go – October 23, 2019
“She probably didn’t comprehend it, but she had given that child the possibility of a life without polio. What an incredible thing it will be when we can do that for every child, from here until the end of time.”
–John Vertefeuille, chief of CDC’s polio eradication branch

STAT News: ‘The switch’ was supposed to be a major step toward eradicating polio. Now it’s a quandary – September 13, 2019
“Dr. Stephen Cochi, senior advisor to CDC’s global immunization program, said it would also help if the WHO agreed to treat each discovery of type 2 vaccine viruses as what’s known as Level 3 emergency, the way a discovery of wild poliovirus would be. Currently they are deemed a Level 2 event.”

Polio Eradication: Progress and Challenges on the Road to Zero


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October 24, 2019 is not only World Polio Day, but also the 30th anniversary of the Global Polio Eradication Initiative (GPEI). CDC has collaborated with our partners for decades to work towards eradicating this disease across the globe. In those 30 years, the world has made incredible strides against polio – reducing wild polio cases by over 99% and wiping the wild virus from all but two countries (Pakistan and Afghanistan). Additionally, two of three strains of wild poliovirus have been eradicated, a benefit to future generations and signal of our potential to wipe out all forms of the poliovirus for good.

“The two-remaining polio-endemic countries must reach all children with polio vaccine to achieve zero wild poliovirus cases, and ultimately for the world to achieve polio eradication.“

–Dr. Rebecca Martin, Global Health Center Director

A Nepalese child receives his polio vaccine during an immunization campaign.

A Nepalese child receives his polio vaccine during an immunization campaign.

It takes a village to work towards eradicating polio.

It takes a village to work towards eradicating polio.

Vaccinators mark the pinkies of children who received their polio vaccine with purple markers to keep track of whose been vaccinated.

Vaccinators mark the pinkies of children who received their polio vaccine with purple markers to keep track of whose been vaccinated.

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