How Vaccines Work
This article will give a deep dive into how immunizations affect our bodies.
Date Published: 9/22/24
Introduction
Vaccines have been one of the most effective tools in modern medicine, saving millions of lives by preventing infectious diseases. To understand how vaccines work, we need to learn about the world of immunology. Immunology studies the immune system and how it defends our body against bacteria and viruses.
The Immune System
The immune system is like a highly trained army, constantly on the lookout for harmful organisms that can cause disease. When a pathogen enters your body, the immune system recognizes it as foreign and launches an attack. This involves various types of immune cells, such as white blood cells, that identify, target, and destroy the virus. One of the key components of this system is the production of antibodies, proteins that target and kill pathogens.
How Vaccines Train the Immune System
Vaccines work by training the immune system to recognize pathogens without causing the disease. They do this by introducing a harmless form of the pathogen into the body. This could be a dead or weakened version of the virus or bacteria. Once the immune system encounters this harmless version, it responds by producing antibodies. These antibodies remain in the body, ready to fight the real pathogen if you’re ever exposed to it.
Types of Vaccines
There are multiple types of vaccines, each designed to prepare the immune system in different ways:
Live Attenuated Vaccines: These contain a weakened form of the virus or bacteria that is still alive but unable to cause disease in healthy individuals. Examples: Measles, mumps, and rubella (MMR) vaccine.
Inactivated Vaccines: These contain pathogens that have been killed. Although they can't cause disease, they can still stimulate an immune response. Example: The Polio vaccine.
Subunit, Recombinant, and Conjugate Vaccines: These vaccines use specific pieces of the pathogen to cause an immune response. Example: The HPV vaccine.
mRNA Vaccines: A newer type of vaccine, mRNA vaccines use a small piece of the virus’s genetic material to instruct cells in the body to produce a protein that triggers an immune response. Examples: The Pfizer and Moderna COVID-19 vaccines,
Immune Memory
One of the most interesting aspects of vaccines is that they create "immunological memory." After vaccination, your immune system remembers the pathogen. If you encounter the real pathogen later, your body can quickly produce the antibodies needed to neutralize it before it can cause sickness. This is why vaccines are so effective in preventing diseases like smallpox, polio, and more recently, COVID-19.
Herd Immunity
When a large percent of the population is vaccinated, it creates "herd immunity", which provides indirect protection to people who cannot be vaccinated, like newborns or people with medical conditions. This collective immunity helps prevent outbreaks and can eventually lead to the eradication of diseases.
The Future of Vaccination
Advances in science are leading to the development of new and more effective vaccines. Researchers are exploring vaccines for diseases like HIV and malaria, as well as universal vaccines that could protect against all strains of the flu or coronaviruses. With continued research and innovation, vaccines in global health continue to expand.
Works Cited
Plotkin, Stanley A., et al. Vaccines. 7th ed., Elsevier, 2018, https://www.elsevier.com/books/vaccines/plotkin/978-0-323-35761-6.
Murphy, Kenneth, and Casey Weaver. Janeway's Immunobiology. 9th ed., Garland Science, 2017, https://www.garlandscience.com/janeways-immunobiology-9e/.
Rappuoli, Rino, et al. "Vaccines, New Opportunities for a New Society." Proceedings of the National Academy of Sciences, 2014, https://www.pnas.org/content/111/34/12288.
Koff, Wayne C., et al. "Vaccines and Global Health: The Need for New Vaccine Development." Vaccine, 2013, https://www.sciencedirect.com/science/article/pii/S0264410X12017627.
