What Is A Vaccine?

This article is part of a series explaining the COVID-19 pandemic. Please consider starting at Part 1: What is a virus or check out the whole series by clicking the button below.

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What Is A Vaccine?

The first vaccine was used in 1796 when Edward Jenner inoculated an 8-year-old boy with material taken from a cowpox sore on another person, under the hypothesis that having cowpox, which typically has very mild symptoms in humans, would protect against smallpox. Jenner later variolated the boy with smallpox material to test the boy’s reaction: he remained healthy. (HistoryofVaccines.org). As word began to spread about these results it grew in popularity, eventually leading to mass adoption. In fact, the very word, vaccination, is derived from Jenner’s experiment. Vacca is the Latin word for cow. (Science)

Some Terminology

Variolate - As early as 1000CE in Asia, variolation was used as a measure to try and prevent people from dying of smallpox. Variolation is the process of deliberately infecting someone with a controlled dose of smallpox such as dried scabs from smallpox sores.

Innoculate - To implant a microorganism into an environment. In medicine, it typically refers to vaccinations to prevent disease, but in general microbiology, it can be used more generally.

Vaccinate - To innoculate with the specific intent of preventing disease

Immunize - To make someone immune to a disease, to prevent them from getting a disease.

Sources:

National Library of Medicine - Smallpox: A Great And Terrible Scourge

Dictionary.com - “Vaccinate” vs. “Inoculate” vs. “Immunize”: What Are The Differences?

Since then, vaccines have been used as a medical technology to control and, in some cases, eradicate harmful pathogens. As we previously mentioned in our Understanding COVID-19 series, a pathogen is an organism such as “a bacterium, virus, parasite or fungus that can cause disease within the body”

Unlike medicines such as antibiotics, which are usually prescribed once a person has become infected with a pathogen to cure or ease the symptoms of a disease, vaccines work with our natural immune system and responses to prevent becoming infected in the first place, or to reduce the severity of an illness for which you have been inoculated (Immunize BC – What are vaccines?).

“Vaccines train your immune system to create antibodies, just as it does when it’s exposed to a disease. However, because vaccines contain only killed or weakened forms of germs like viruses or bacteria, they do not cause the disease or put you at risk of its complications.”

-World Health Organization

Most, but not all, vaccines introduce weakened or deactivated versions of a pathogen, called antigens, to your immune system through injection, or oral consumption (World Health Organization – Vaccines and Immunization). Once the antigens are introduced, our immune system begins to develop antibodies for that specific antigen, which then combat the pathogen spreading throughout and infecting the body. Our immune system also remembers the antibodies it produces for specific antigens to protect against the same harmful pathogens in the future. This process of developing antibodies and remembering them is called immunization or becoming immune to that pathogen (IMMUNIZE BC – How Do Vaccines Work).

World Health Organization - How Do Vaccines Work?

Side Effects

Because vaccines use damaged or inactivated versions of the pathogen, they are very safe, although there can be side effects. Many people feel some muscle discomfort where they received the vaccine if injected, or a few side effects, this is called an inflammatory reaction. These reactions mean your immune system is hard at work doing its job developing the antibodies to fight the pathogen you were vaccinated for. Common side effects may include muscle aches, fever, chills, or headaches (Government of Canada – Vaccine safety, concerns, and possible side effects).

“It is much safer to get the vaccine than to get the disease it prevents.”

-IMMUNIZE BC

Effectiveness of Vaccines

In the late 18th century, smallpox was a pervasive disease. “On average, 3 out of 10 people infected died of from the disease” (Center for Disease Control - History of Small Pox), while those who survived were left with severe scarring of the skin.

In the last decade of Jenner’s life, the London Bills of Mortality documented 7,858 deaths from smallpox—down from 18,447 deaths in the last decade before vaccination (1791-1800).

Over time, Jenner’s work inspired others to improve upon the original smallpox vaccine and develop vaccines for additional pathogens such as rabies, diphtheria, measles, polio, and many other diseases, including COVID-19.

On May 8, 1980, 196 years after Jenner inoculated the 8-year-old boy, the WHO declared smallpox eradicated from the planet. (CDC: History of Smallpox)

“We now have vaccines to prevent more than 20 life-threatening diseases, helping people of all ages live longer, healthier lives. Immunization currently prevents 2-3 million deaths every year from diseases like diphtheria, tetanus, pertussis, influenza, and measles.”

-World Health Organization

Infographic: Government of Canada - Vaccines Work

Immunization And Herd Immunity

Vaccinations protect us as individuals against harmful pathogens, but they also help protect others in our communities. Once you become immune to a pathogen by being vaccinated, your chances of spreading the virus are reduced or eliminated.

When enough people become vaccinated against a pathogen in a community, others who cannot be vaccinated are protected, creating an effect called herd immunity, or population immunity. On a basic level, when enough people in a community are vaccinated, pathogens have a difficult time finding a suitable host to replicate in, because the majority of people the pathogen encounters are immune.

When a vaccine becomes available, it is important for as many people to become vaccinated as possible. This is because there are some vulnerable people in our communities that cannot be vaccinated due to underlying health conditions, allergies to vaccine components, or because they do not have access to a vaccine. For example, as of this writing (April 9, 2021), there are no COVID-19 vaccines approved for use in children under the age of 16, though clinical trials are underway.

Watch this brief graphic animation from Harvard Medical School to see how herd immunity works.

Dr. Kara Loos, a genomics research associate from the Institute for Microbial Systems and Society (MISS) at the University of Regina, says that different pathogens require different percentages of herd immunity. For example, Measles is one of the most contagious pathogens on Earth. According to the World Health Organization, it is estimated that 95% of a community needs to be vaccinated against measles to create the required herd immunity to protect the remaining 5% of the population who cannot be vaccinated. By comparison, herd immunity for the polio disease is achieved when about 80% of the population is vaccinated (World Health Organization – Herd Immunity, Lockdowns and COVID-19).

At the beginning of the COVID-19 pandemic, some countries felt that the best way to deal with the disease was through natural herd immunity (Reuters). In all cases, this proved to be disastrous as hundreds of thousands of people died, often overwhelming available health resources. Herd immunity for COVID-19 must be achieved through vaccination. “The proportion of the population that must be vaccinated against COVID-19 to begin inducing herd immunity is not known. This is an important area of research and will likely vary according to the community, the vaccine, the populations prioritized for vaccination, and other factors” (World Health Organization).

An upcoming article will focus specifically on COVID-19 vaccines, and on the different types of vaccines available in the fight against COVID-19. However, this much is clear: the best vaccine for you is the one available to you right now.

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The COVID-19 Vaccine(s)

This article is part of a series explaining the COVID-19 pandemic. Please consider starting at Part 1: What is a virus or check out the whole series by clicking the button below.

The different COVID-19 vaccines available in the world represent a tremendous success by science. These vaccines were developed, tested, and proven safe very quickly, saving millions of lives around the world.

These vaccines were so successful, in fact, that some people questioned their safety or are/were hesitant to take the vaccine because they thought that it may have been rushed.

The truth is, scientists from all over the world worked on finding vaccines for COVID-19. The seemingly rapid development of the vaccines was not due to corner-cutting or shortcuts but was due to the immense worldwide funding, focus, and collaboration as a result of the severity of the pandemic.

All of the vaccines which have been approved around the world are safe and effective against preventing serious hospitalization and death from COVID-19. In all cases, the small risk of side effects from the vaccines far outweighs the potential risks of contracting COVID-19.

The best vaccine for you is the one that has been approved and which you have access to.

Vaccines that have been approved in different countries around the world include:

Sinovac-CoronaVac - developed by Beijing-based Sinovac. CoronaVac uses inactivated virus toexpose the bodies immune system to the virus without risking serious disease. (https://www.who.int/news/item/01-06-2021-who-validates-sinovac-covid-19-vaccine-for-emergency-use-and-issues-interim-policy-recommendations)

Sputnik V - Developed in Russia, the Sputnik V COVID-19 Vaccine uses a recombinant adenovirus approach. Each of the two doses uses a different adenovirus as vectors (AD26 and Ad5) as vectors to overcome any pre-existing adenovirus immunity in the population. (https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(21)00191-4/fulltext)

Pfizer/BioNTech (Comirnaty) - This is an mRNA vaccine. This vaccine uses mRNA to teach our body how to create a protein that triggers an immune response inside our bodies. Our bodies produce the protein, and also produces the antibodies that protect us from those antibodies. mRNA vaccines do not change our DNA and the cells which produce the protein break down once the protein is complete. (https://www.canada.ca/en/health-canada/services/drugs-health-products/covid19-industry/drugs-vaccines-treatments/vaccines/pfizer-biontech.html)

Moderna (Spikevax) - Like the Pfizer BioNTech vaccine, this is also an mRNA vaccine. mRNA vaccines teach our cells how to make a protein that will trigger an immune response without using the live virus that causes COVID-19. Once triggered, our body then makes antibodies. These antibodies help us fight the infection if the real virus does enter our body in the future. (https://www.canada.ca/en/health-canada/services/drugs-health-products/covid19-industry/drugs-vaccines-treatments/vaccines/moderna.html)

Astra-Zeneca/COVISHIELD (Vaxzevria) - Sometimes known as the Oxford Vaccine, this vaccine uses a harmless virus (the adenovirus) as a delivery system. This adenovirus is not the virus that causes COVID-19; you can not get COVID-19 from this vaccine. There are many different types of adenoviruses, including some that cause colds in humans and that infect other species. Scientists have been using these viruses for decades to deliver the instructions for proteins. (https://www.canada.ca/en/health-canada/services/drugs-health-products/covid19-industry/drugs-vaccines-treatments/vaccines/astrazeneca.html)

Johnson & Johnson (Janssen COVID-19 Vaccine) - The active ingredient of COVID-19 Vaccine Janssen, also known as Ad26.COV2-S (recombinant), is a recombinant adenoviral vector that contains the sequence that encodes the spike protein (S) of the SARS-CoV-2 virus. This vaccine was approved with a single dose with no booster required. (https://www.who.int/news/item/12-03-2021-who-adds-janssen-vaccine-to-list-of-safe-and-effective-emergency-tools-against-covid-19)

Click Here For A List Of All Vaccines Approved For Use In Canada

Failed Vaccines

With the large number of successful vaccines which have been deployed around the world and the speed with which they were deployed, some people may have felt that developing a vaccine was easy. This isn’t true; these vaccines were developed quickly due to the billions of dollars of research money, time, collaboration, and effort that was put into developing the vaccines. Hearing about the successful vaccines is an example of Survivorship Bias - a type of cognitive bias that makes us forget about the base rate of failures and instead focus on the relatively small number of successes (https://fs.blog/2019/12/survivorship-bias/).

In fact, some of the world’s largest and most well-known vaccine makers were unable to develop or chose not to develop COVID-19 vaccines, including GlaxoSmithKline, Merck, and Sanofi (https://www.ft.com/content/657b123a-78ba-4fba-b18e-23c07e313331). Australia had been working on their own COVID-19 vaccine at the University of Queensland using a ‘molecular clamp’ approach. The development of this vaccine, which showed promise in early testing, was also halted (https://www.sciencemag.org/news/2020/12/development-unique-australian-covid-19-vaccine-halted).

The bottom line: you can feel safe knowing that when a vaccine is approved for use that it has been thoroughly tested and is safe.

COVID-19 Vaccine Conspiracy Theories

It’s not hard to discover conspiracy theories about almost anything on the internet, COVID-19 vaccines included. From microchips to infertility, misinformation about these life-saving vaccines abounds on the internet.

Sometimes conspiracy theories begin as a joke, other times there is a motive - because the originator wants to make a name or money for themselves or a movement, for example.

Why do people come to believe in conspiracy theories? There are many reasons, but they often stem from a need to explain, accept, or rationalize a discrepancy between what one believes and what one experiences. They can make one feel safe when overwhelmed in the world - like you have it all figured out.

In the case of COVID-19 vaccines, those conspiracy theories can cost lives - the lives of the people who believe in them, and the people around them. It is important to think critically and rely on the advice of established health organizations such as the World Health Organization, Health Canada, and the US Center for Disease Control.

Additional Resources:

WHO COVID-19 Dashboard - https://covid19.who.int/

COVID-19 Vaccines Side Effects - https://www.who.int/news-room/feature-stories/detail/side-effects-of-covid-19-vaccines

COVID-19 Vaccines in Canada - https://www.canada.ca/en/public-health/services/diseases/coronavirus-disease-covid-19/vaccines.html

Understanding MRNA - https://www.cdc.gov/coronavirus/2019-ncov/vaccines/different-vaccines/mrna.html

Understanding Viral Vector-Based Vaccines - https://www.canada.ca/en/health-canada/services/drugs-health-products/covid19-industry/drugs-vaccines-treatments/vaccines/type-viral-vector.html

Government of Saskatchewan COVID-19 Info Page - https://www.saskatchewan.ca/coronavirus

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