Science

A look back at the development of three landmark vaccines – Québec Science

Vaccines have greatly improved life expectancy by protecting us against formidable germs. While waiting for the arrival of the vaccine against COVID-19, let’s dive back for a moment into the developments of vaccines that have made history.

Smallpox is an infectious disease of the past: the World Health Organization (WHO) declared it eradicated in 1980. But we must not forget that it has wreaked havoc for millennia, especially in children.

Very contagious, it caused in particular a fever and the appearance of pustules and killed approximately 30% of the patients. Those who survived were often disfigured by extensive scars.

At 17e century, in Asia and Africa, we find a practice resembling the ancestor of vaccination: variolation. The “pus” from the lesions of a mildly ill person was used to infect a healthy person. “The idea was that we could thus develop immunity while being subjected to the disease in a limited way”, underlines Laurence Monnais, professor of history at the University of Montreal. The procedure was not without danger: it is estimated that about 1 to 2% of people participating in this exercise died from it.

This practice of variolation has spread to Europe and the Americas. It had a significant effect on the decline in mortality associated with smallpox. Sign that this process slowed down the disease, “the variolation of entire villages has led to a decrease in mortality due to smallpox”, remarks Peter Razzell, researcher in historical demography at the University of Essex, who underlined it in his book The Conquest of Smallpox published in 1977.

Vaccine to fight smallpox

In 1757, in England, thousands of young people were treated in this way in order to prevent disease. Among them, an 8-year-old boy named Edward Jenner, who would become a doctor years later.

At the end of the 18the century, Dr. Jenner has heard of farm women who appeared to be immune to smallpox. They had contracted cowpox (called vaccinia), a disease similar to human smallpox, but much less serious.

To test the hypothesis that vaccinia patients were subsequently protected against smallpox, Edward Jenner inoculated the contents of the lesions of a dairy woman with vaccinia into a child. After a few days of showing mild symptoms, the boy was doing well. The Dr Jenner then proceeded to the classic variola technique, thus with lesions from a smallpox patient. Result? The child did not develop any symptoms. The doctor calls this new technique: vaccination. “At that time, we did not know bacteriology and we did not know how immunology works”, adds Laurence Monnais, to emphasize this historic discovery.

It took a long time before the technique was democratized. As an article by on major epidemics, smallpox marked the year 1885 in Canada. The virus arrived in Montreal by train: its host was a passenger from Chicago.

He goes to the hospital for treatment. It was the start of a deadly outbreak that left more than 5,864 dead and 13,000 disfigured, mostly French Canadians. Even though the smallpox vaccine is available, many people question it and will not want to be vaccinated. This movement will go as far as riots in the streets of the city.

Polio of the last century

A Swedish boy who was vaccinated against polio in 1957. Image: Ingemar Berling / Pressens Bild

Poliomyelitis disease, often called polio, has been around for a long time: hieroglyphics have been found dating back to 2000 BC. AD which show people with atrophied legs and arms. The polio virus attacks the nervous system and motor neurons, causing paralysis. The muscles involved in breathing are particularly affected.

To prevent the death of patients unable to use their muscles to breathe, professors at Harvard University even invented steel lungs in 1927. The device consisted of a kind of metal tunnel in which the patient took square; only his head remained outside. Mechanical pumps varied the pressure inside the chamber to aid breathing.

It was in the late 1920s that polio epidemics reached Canada. Quebec experienced an outbreak in 1931 and 1932. The virus was spread through contact with an infected person or through contaminated food. As with smallpox, the disease attacks young children more severely. It is estimated that between 1949 and 1954, more than 10,000 Canadians became paralyzed from this disease.

US and Canadian scientists are working to better understand the virus to create a vaccine. Connaught Medical Research Laboratories in Ontario successfully cultivated the virus in the laboratory. This feat will then allow the team of American virologist Jonas Salk to manufacture a vaccine. On April 12, 1955, it was announced with great fanfare that the vaccine, whose effectiveness varied between 60 and 90%, worked and would be marketed in both countries. The Ontario laboratory will collaborate again with American researchers in 1962 to produce an oral vaccine against polio.

Polio still exists today, but on a smaller scale. It still exists in developing countries. According to data from the WHO, there were 12 polio outbreaks in 2019 in countries such as Mozambique, Indonesia, Iran, Myanmar and Sudan.

Killer tuberculosis

Unlike the other two diseases mentioned above, which are caused by viruses, tuberculosis is caused by bacteria. Another difference: it is still a serious problem in our modern age. According to the WHO, 1.5 million people died from it in 2018.

This disease that affects the lungs has also been around for millennia. It would first have reached only animals before evolving into a species transmissible to humans.

An advertisement to encourage people to get vaccinated against tuberculosis. Image: Wikimedia Commons.

At the beginning of the 20e century, two French scientists are trying to develop a vaccine against tuberculosis. They are the doctor Albert Calmette and the veterinarian Camille Guérin. These researchers are carrying out their work on a bacterial strain of tuberculosis found in cattle. They grow the bacteria in beef bile and potatoes. However, to keep the bacterial population alive, they must, after about twenty days, transfer these bacteria to a new medium.

The researchers turned out to be very patient: they repeated this maneuver for 13 years. But it paid off: the bacteria lost their virulence. The researchers carried out tests on animals to confirm that their bacteria, which had become harmless, did stimulate the immune system of the cattle without making them sick. This is how the BCG vaccine (or Calmette and Guérin bile vaccine) was born in 1912.

Quebec doctor Armand Frappier worked with these two French researchers during his studies in the 1930s. He returned to Quebec with, in his suitcases, attenuated bacteria to produce a vaccine here, in a laboratory at the University of Montreal . His work helped demonstrate the effectiveness of this vaccine against tuberculosis, a disease that caused him to lose his mother and other members of his family. While microbiology was a booming field in the province, Armand Frappier then founded the Montreal Institute of Microbiology and Hygiene in 1938. It was then renamed the Armand-Frappier Institute in 1975 in his honor.

Over the past century, other important vaccines have been developed. We can especially think of those against influenza and measles. Right now, thousands of scientists are busy designing COVID-19 vaccines. Without a doubt, these will also make history.

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