Biological Battlefield: How Vaccines are the Drill Sergeant of Your Body's Basic Training

By: Ezra Sussman

In the 1970s and 1980s in North America the seemingly inevitable event of a child contracting chicken pox was being controlled by parents in the form of “pox parties”.¹ These were events in which a parent would bring their otherwise healthy child to play with a child who was ill with the varicella-zoster virus (VZV) with the hopes that their child would become infected, develop symptoms of chicken pox and then never get it again. 

This behaviour has existed in many forms since at least the 15th century and can possibly even be dated back to around 200 BCE.² Even without microbiology knowledge, people noticed that there were some things people could get sick with once and then seemingly never again. For the most part, smallpox was what people were hoping to contract with the hopes that they could get it at a time when they were well and the illness would not be as terrible. The practice, known as variolation, which is effective to an extent, does require a full course of an illness meaning that there can be multisystemic health issues or long term damage if a person cannot fight it properly.

For many microorganisms, our body can learn to fight them based off past experiences. Special immune cells known as B and T lymphocytes create specific proteins called antibodies that fight foreign bodies (such as viruses and bacteria).³ In a healthy person, when these antibodies have been made once, it is much easier to make them again meaning that if the same or similar pathogen enters the body, it can be fought off quickly with little or no symptoms of being “sick”. This is called acquired immunity.⁴

In 1796 Dr. Edward Jenner, a physician, conducted an experiment in which he intentionally infected a patient with the much less severe, but seemingly similar disease, cowpox .² He observed that a later infection with smallpox resulted in no reaction even though it normally made patients severely ill. The Latin word for cow, vacca, is where we get the term vaccine. 

Since then, there have been many iterations of vaccines for different conditions with slightly different mechanisms, but the core principle is the same: our bodies know how to fight pathogens, and they do it well, we just need to teach them in a controlled environment. Pilots learn skills in an airplane simulator, medical students do surgical simulations and the human immune system can learn from vaccines before something that poses a massive risk to our health presents itself as threat.

Nearly every vaccine on the market is a weakened, dead, or structurally similar virus or bacteria to the disease it is trying to prevent.⁵ For a healthy person, fighting this off will add to our acquired immunity and any symptoms, (sore arm, low grade fever, fatigue) that emerge in the coming days will be a significantly milder, shorter term and safer. Even if a disease is very uncommon as a result of most of the population have acquired immunity to it (such as measles), people with certain immune conditions may be unable to put their immune system under the burden of a vaccine. This means there are benefits to getting vaccinated for the sake of the population, also called the “herd immunity”.

Certain conditions require vaccines regularly due to the virus or bacteria changing, such as influenza (the flu), and others, like chicken pox and the human papillomavirus (HPV) may only need to happen once in a lifetime and can prevent long term complications like shingles or cancer.² Some vaccines may only be recommended if travelling to areas of the world where a certain pathogen is more prevalent, such as malaria. 

Vaccines have a long and safe history of preventing deaths from viruses and bacteria and regular vaccinations are one of the main reasons the life expectancy in Canada has risen from less than 60 to over 80 years old since the mid 20th century when they became commonplace.⁶

References

1. CDC. Chickenpox (Varicella). 2025 [cited 2025 Dec 3]. About Chickenpox. Available from: https://www.cdc.gov/chickenpox/about/index.html

2. A Brief History of Vaccination [Internet]. [cited 2025 Dec 3]. Available from: https://www.who.int/news-room/spotlight/history-of-vaccination/a-brief-history-of-vaccination

3. Cano RLE, Lopera HDE. Introduction to T and B lymphocytes. In: Autoimmunity: From Bench to Bedside [Internet] [Internet]. El Rosario University Press; 2013 [cited 2025 Dec 3]. Available from: https://www.ncbi.nlm.nih.gov/books/NBK459471/

4. Definition of acquired immunity - NCI Dictionary of Cancer Terms - NCI [Internet]. 2011 [cited 2025 Dec 3]. Available from: https://www.cancer.gov/publications/dictionaries/cancer-terms/def/acquired-immunity

5. CDC. Vaccines & Immunizations. 2024 [cited 2025 Dec 3]. Immunity Types. Available from: https://www.cdc.gov/vaccines/basics/immunity-types.html

6. OECD. Canada [Internet]. OECD Publishing; 2025 [cited 2025 Dec 3]. Available from: https://www.oecd.org/en/publications/health-at-a-glance-2025_15a55280-en/canada_41ea57c7-en.html