Author: Sara Habibipour
Before Jonas Salk’s revolutionary vaccine in the 1950s, poliovirus paralyzed more than 15,000 people each year in the United States. Thanks to widespread vaccination, wild polio has been eradicated in the United States, with no new cases occurring since 1979. Currently, there are only two countries where wild polio is still endemic: Afghanistan and Pakistan. As a whole, the world has been moving closer towards the elimination of polio, but setbacks remain due to communities that oppose vaccination efforts, polio workers coming into contact with war, etc., leading to the resurface of polio in southern Africa in 2021 and Ukraine in 2022, among many other countries including the United States in 2022.
Why has eradication proven to be so difficult? What is getting in the way of global elimination of wild poliovirus, and what are steps that some countries have taken that can be applied to others?
First of all, what is polio?
Poliomyelitis (polio) is a highly infectious viral disease that is most often transmitted via contaminated water and it can survive for months outside the body. About 75% of infections are asymptomatic, allowing the disease to spread throughout the body undetected; once it reaches the brain and spinal cord, the virus can cause paralysis and death.
Since there is no cure for polio, public health officials have focused on mass immunization to control the disease. There are two forms of immunization: the first is the inactivated polio vaccine developed by Jonas Salk in the 1950’s which is administered via a one-dose injection, and the other is the oral polio vaccine which was developed by Albert Sabin in 1961 which contains live strains of virus and is very efficient, but requires several boosters to be effective.
In addition to wild poliovirus, there is vaccine-derived poliovirus which occurs when the weakened strain from the oral vaccine mutates in under-vaccinated communities to behave more like the wild virus.
Where is polio an issue now?
Polio remains endemic in Afghanistan and Pakistan, meaning that transmission of poliovirus has never been interrupted. Of the world’s 110 cases of polio in 2020, 67% of those were found in Pakistan, and the rest were found in Afghanistan.
The African region was declared free of wild polio in 2020, however not long after that, it resurfaced in Mozambique and Malawi. There have been several hundred cases of vaccine-derived polio not only in Africa, but in the United States and Israel as well. New York and London have also recently found polio in wastewater calling for the upkeep of polio vaccination programs.
Areas affected by war are also at high risk of polio transmission due to disrupted health systems, under-vaccination, and contaminated water in refugee camps. Public health experts have been particularly concerned about the rise in vaccine-derived polio cases in Ukraine since early 2022.
What are the challenges to eradication?
The polio vaccine is quite difficult to administer; for example, the oral polio vaccine needs to be administered several times and kept refrigerated. Further, polio is extremely contagious and most never show symptoms.
Another major challenge is the mistrust of Western vaccination campaigns. Despite national governments’ support for polio vaccination programs, the communities that need the vaccinations are often hesitant to receive vaccinations. Polio immunization workers have often come into contact with militants; more than 70 workers have been targeted in Pakistan since 2012. This aligns with the Tehrik-e-Taliban’s (TTP) ban on polio vaccinations in Pakistan in 2012. TTP leaders said that the ban was due to U.S. drone strikes, however there was also lingering mistrust due to a medical team who ran a hepatitis B vaccination program in 2011 to gather information on Osama bin Laden’s whereabouts. Further, 8 were killed in northern Afghanistan in February 2022, leading the United Nations to halt vaccination programs in this region. These events have set global health efforts back by decades.
Along with mistrust comes misinformation. In 2019, for example, Khyber Pakhtunkhwa burned down a healthcare facility in Pakistan after misinformation spread that the vaccinated children had become ill due to being given expired vaccines. Misinformation is particularly high in conflict-afflicted zones, such as the areas occupied by Khyber Pakhtunkhwa in Pakistan and Boko Haram in northern Nigeria. A 2005 study by the Department of International Development showed that there is a geographic disparity in immunization rates across Nigeria, with rates being as low as 3.7 to 6% from the Northwest to the Northeast (where Boko Haram is most active), and 33 to 45% from the Southwest to the Southeast. This also aligns with the call for a boycott by religious and political leaders in Nigeria in 2003.
What is being done, and what needs to be done?
To combat vaccine derived polio, scientists have been developing a new version of the oral vaccine. It has been shown to be clinically effective and over a hundred million doses have been administered. Although this sounds like a lot, widening of its availability has been slow, and the WHO has encouraged countries to keep using the resources they have rather than waiting for the new vaccine.
In response to a paralytic case in Malawi, UNICEF launched a new campaign in 2022 to vaccinate twenty-three million children across the southern African country and its neighbors. The Malawian government and the WHO set up surveillance sites across the country and the CDC is currently assisting with surveillance.
Dr. Folake Olayinka was a leader of the Nigeria polio vaccination program. According to her, oftentimes mothers had to seek permission from their husbands before they could allow the children to be vaccinated or access health services. “Even when they understood the value, women did not have decision-making power" (interview with Polio Global Eradication Initiative).
In Nigeria, men originally started out as polio workers, but it quickly became apparent they were missing children under five because they were not allowed into homes due to cultural norms. The solution became to hire women as polio workers to reach populations being missed. The polio program brought women into the workforce in ways that hadn’t been done before. The polio program was one of the first programs bringing women out of their homes, particularly respected elderly women, training them how to speak to and educate other women and community members. They also received stipends to compensate them financially.
Women became the heart of polio eradication in northern Nigeria. Through developing culturally competent public health programs across the globe, we can more efficiently control disease transmission and eradicate preventable diseases.
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Sources:
https://www.cfr.org/backgrounder/why-hasnt-world-eradicated-polio#chapter-title-0-6