Epidemics Past and Present: Polio and COVID-19

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An unvaccinated @agmoore, a few years before introduction of the Salk vaccine

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In 1954 I took part in an audacious public health experiment. I was a recruit, not a volunteer. The stakes were so high that public health officials went forward despite significant risk. This was the first widespread test of the Salk polio vaccine. 1.6 million children across the U.S., Canada and Finland were enrolled.

I remember, in those days, we feared polio, even the youngest among us. We were haunted by images of afflicted children in iron lungs. Many of us personally knew of classmates, or neighborhood children who had been stricken.

Patients in Iron Lungs: Mechanical Respirators
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Henderson and Both Respirators are shown. Image credit: Wellcome Trust. Used under a CC 4.0 license

The iron lungs, as they were called, enabled polio sufferers to breathe if their chest and diaphragm muscles were paralyzed. Sometimes this intervention was temporary, and sometimes it became a life sentence. I think, more than anything else about polio, this image struck terror in the hearts of children.

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There was a diffuse, palpable fear about polio, not unlike the fear surrounding COVID-19 today. When the Salk vaccine was finally introduced, Jonas Salk was regarded as a savior.

There are parallels between polio of that time and the COVID-19 pandemic of our time. These parallels may help to illuminate some of the challenges we face as we move forward toward treatment, management and vaccination.
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1963 Poster Promoting the Sabin Oral Vaccine
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Image credit: CDC, public domain.

The competition between Salk and Sabin was quite intense. Salk used a 'killed' virus and Sabin used a weakened 'live' virus. Sabin's was cheaper and easier to administer, but in a very small number of cases actually caused paralytic polio. Eventually, this risk led, in the U.S. at least, to discontinuing use of the oral vaccine.

Asymptomatic Carriers and Mortality

One similarity between COVID-19 and the polio virus is the role of asymptomatic carriers. In children with polio, only about 24% of those who contract the virus will show symptoms.These symptoms are generally a low-grade fever and sore throat. And, of all those who contract the virus, only about 1% will experience paralytic polio. Of these, between 2 and 5% will die. In the adult population, mortality from paralytic polio is much higher--between 15 and 30%. In this, polio is like COVID-19, in that adults afflicted with severe disease suffer a higher mortality.

1957 March of Dimes Poster
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Image Credit: March of Dimes Foundation, public domain

Every year, during the campaign to find a polio vaccine (and once it was discovered, to get people to use it), the March of Dimes Foundation would pick a poster child to be the face of the organization. The child in the 1957 poster was identified as Martha Ann King. She is said to have contracted polio when she was four days old. I tried to discover what her future was like after the poster campaign, but couldn't find any information.

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It was once thought that adults could not be asymptomatic carriers of the disease, and it was believed that older children and adults were largely immune. The focus was always on vaccinating children under the age of 5. However, a recent study out of India showed that a significant portion of older children and adults may contract the disease and also be asymptomatic spreaders.
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R0 (R Naught) Diagram Showing How Infection Spreads in Two Diseases (Ebola and Sars)
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Image credit: Kiera Campbell used under a CC 4.0 license

R0 (R Naught) Values for COVID-19 and Polio

R number stands for "effective reproduction rate" in "a completely susceptible population". R0 values are helpful in estimating what percent of a population needs to be vaccinated in order for herd immunity to kick in. According to the Johns Hopkins Bloomberg School of Medicine, the R0 value for polio is 6. According to an article in Science ("Substantial undocumented infection facilitates the rapid dissemination of novel coronavirus (SARS-CoV-2", May 1, 2020), the R0 rate for COVID-19 is 2.38. Of course, so much more is known about polio than COVID-19. With polio, it is estimated that 83% of the population would have to be vaccinated in order to achieve herd immunity (according to Johns Hopkins). One source, writing in Science Alert ("Here's Why Herd Immunity Won't Save Us From The COVID-19 Pandemic", March 2020) estimates that herd immunity for COVID-19 will be achieved when 70% of the population is vaccinated.

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Lockdowns and Quarantines
In 1916, in the midst of a raging polio epidemic, the U. S. Public Health Service declared that there was "no specific treatment of established value in poliomyelitis". In that circumstance, health officials were left with scant tools to fight the disease. Two of these tools were the institution of hygiene/sanitation measures and, control of people's movements.

Quarantine Notice Threatening Imprisonment
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This notice was placed in the window of homes where someone had been diagnosed with polio. All who lived there were in mandatory 'lockdown', on pain of fine and//or imprisonment. It is assumed this image is credited to a government agency, but in any case the picture is in the public domain.

Today, health officials find themselves in a similar position as they try to battle COVID-19. There is no vaccine, and, as the Mayo Clinic reports, "Currently, no medication is recommended to treat COVID-19, and no cure is available".(the slight benefit noted for remdesevir in severely ill patients notwithstanding). The only effective public health measures available for fighting this disease are the institution of hygiene/sanitation measures and following a policy of behavior control--recommending/requiring social distancing and mask wearing.

Just as there are people today who doubt the efficacy of social distancing and mask wearing, there were people in past polio epidemics who doubted public health efforts to address the situation. During the 1916 polio epidemic, for example, Town of Oyster Bay (NY, USA), Supervisor, James H. Cox, "repeatedly questioned the scientific basis for quarantine regulations, arguing physicians seemed divided about the cause and spread of polio."

First Electron Microscope, Invented by Ernst Rusk, 1933
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Image credit: J Brew, uploaded on the English-speaking Wikipedia by en:User:Hat'nCoat. CC 3.0 license

As researchers today try to develop a treatment/vaccine for COVID-19 they have one advantage over those who fought early polio epidemics: They understand exactly what a virus is and can work with it in the laboratory. In 1916, researchers had "discovered" several viruses, but had not been able to visualize a virus under a microscope. That ability would not be theirs until the invention of the electron microscope.

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Microscopic Images of Polio and COVID19 Viruses
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COVID 19 image Credit: NIAID CC license 2.0
Polio credit: F.P. Williams, U.S. EPA public domain

The polio virus (there are several strains) has a simple structure. Like all viruses, it is a bit of genetic material looking for a cell that it can invade and take over. The polio virus is described as relatively featureless, unlike COVID-19, which has a spiky envelope that looks a little like a crown (corona), as you can see in the picture. Viruses have to find a way to get inside a cell, a doorway that will open and let them pass through the cell membrane. It's like aliens in the movie "Invasion of the Body Snatchers": the virus needs to hijack a cell in order to carry on its work. What is that work? Propagate, and send millions of virions into the host's bloodstream to take over more cells.

Poster From the 1956 Movie, Invasion of the Body Snatchers
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Image credit: Allied Artists Picture Corporation. public domain, published before 1978 without copyright notice

With their limited knowledge of the polio virus, health officials during early polio epidemics were at a loss to explain its spread and understand its mode of transmission. Today, not only has COVID-19 been directly observed with instruments even more powerful and precise than the electron microscope, but the full genomic sequence of the virus is also available for study.

Routes of Transmission
Polio is an enterovirus and COVID19 is a corona virus. As an enterovirus, the polio virus favors spread through the oral/ fecal route. However, any close contact with an infected person can lead to infection. Indirect infection is also possible--one route is through swimming in contaminated water.
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Diagram Showing Fecal Oral Route of Transmission
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Image credit: UNICEF Philippines and Luis Gatmaitan, Gilbert F. Lavides. CC 2.0 license. This F-diagram (feces, fingers, flies, fields, fluids, food) was obviously designed to show children how to protect themselves from infection by an enterovirus.

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COVID19 is spread mostly through droplets and fomites (surfaces). According to Johns Hopkins, aerosolization is a distinct possibility, which would mean the virus hangs around longer in the air than a larger droplet and may also go farther than the highly publicized 6 feet. Hopkins' website states that "Stool shedding (of the virus is) also described later in disease, but (it is) uncertain what role, if any, that plays."

Bogus Treatment Claims Abound
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Image credit: U.S. FDA. Parents were desperate to protect their children from the polio virus. This ad promises to help take them "safely through the summer".

Search for a Vaccine: Polio and COVID-19
A New England Journal of Medicine article published in March 2020 (updated May 21) describes "developing Covid-19 Vaccines at Pandemic Speed", and U.S. President Trump has launched Operation Warp Speed in order to find an effective vaccine against COVID-19. The impression given is that never has the world seen such a concerted effort to find a vaccine.
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U.S. President Franklin Roosevelt, in a Wheelchair
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Image credit: American Political History, Public domain
Franklin Roosevelt had been stricken by polio as an adult.
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However, a look back at history reveals that there was at least as great, if not a greater ambition to develop a polio vaccine. This campaign was inspired not only by the thousands of children who were afflicted, but also by the fact that the President of the United States, Franklin Roosevelt, was afflicted. He and his powerful allies helped to spearhead a vaccine development campaign. It was President Roosevelt who founded the March of Dimes, then known as the National Foundation for Infant Paralysis. It was the March of Dimes which funded Jonas Salk's vaccine research.
March of Dimes Poster, 1943
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Image credit: U.S. Office for Emergency Management, Office of War Information, Domestic Operations Branch, artist Charles Henry Alston. Public domain
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Research Subjects: Polio and COVID-19
Humans are the only natural hosts for polio, whereas COVID-19 is a zoonotic virus. It survives in both animals and humans. As research on COVID-19 takes place, it begins with animal studies and then, when found safe there, moves on to humans. The humans in these studies are all volunteers. Even so, ethical concerns are raised about putting lives at risk. In the early phase of polio vaccine development researchers were not so constrained by ethics. Not even Jonas Salk. This was true partly because there was not the option of testing vaccines on animals (because humans are the only natural hosts). Test subjects had to be human, or at least primates. The earliest vaccine trials in the 1930s actually killed, and paralyzed, children.

Almost twenty years after the death of these children, Jonas Salk, and others, moved forward, perhaps more cautiously, but still with very questionable ethics.

Polk State School
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Image credit: National Park Service. Public domain

The human subjects in these trials were disabled children who had neither the awareness nor ability to volunteer themselves. These trials took place at several public institutions: The Polk State School, The Watson Home for Crippled Children, and Letchworth Village Home for the Feeble Minded and Epileptics. Fortunately, no children died or became ill from these experiments. People were so desperate for a vaccine, that little attention was paid to how one was achieved.
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In Memoriam
As I end this blog I take note that for me, this is not just about science, or history. This is about people who are suffering and dying today from COVID-19. I know, or personally know of, some of those people. Below I've included obituaries for others in my region who recently lost their lives to COVID-19. These obituaries put faces on the tragedy of the COVID-19 pandemic. They represent hundreds of thousands who have lost their lives across the world.

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