Education, Vaccines

A Guide to Vaccines

Author Kimberly Hazel , 10-May-2022

If you had to choose one word to describe vaccines, it would be “essential.” Vaccines are essential for protecting humans against disease. They are responsible for eradicating smallpox and controlling polio, measles, rubella, and many other diseases. Despite the benefits of vaccines, some people remain skeptical about their safety and effectiveness. In this blog post, we will explore the history and science of vaccines and dispel some myths surrounding them.


Thanks to vaccines, these formerly deadly illnesses are now much less common, saving countless lives and bringing hope to millions around the world. Vaccines remain an essential tool for protecting public health and ensuring a bright future for generations.

Common Vaccine Myths


Despite the proven effectiveness of vaccines, there is still a lot of misinformation circulating about them. Let’s take a look at some of the most common vaccine myths and dispel them once and for all.


MYTH: Vaccines are not safe.
FACT: Vaccines are among the safest medical products available. They undergo years of testing before they are ever approved for use. Once they are in use, they are continually monitored for safety.


MYTH: Vaccines cause autism.
FACT: There is no link between vaccines and autism. This myth began with a now-debunked study that was published in 1998 and has been debunked numerous times since then.


MYTH: Vaccines are not effective.
FACT: Vaccines are very effective at protecting people from disease. For example, the measles vaccine is 97% effective at preventing measles.


MYTH: You don’t need a vaccine if you’re healthy.
FACT: Even if you’re healthy, you can still spread disease to others who are not vaccinated, like babies or people with weakened immune systems. Vaccines help protect the entire community, not just individuals.


MYTH: Natural immunity is better than vaccine-induced immunity.
FACT: Natural immunity (the immunity you get from actually contracting a disease) is not always better than vaccine-induced immunity. For one thing, natural immunity is not always complete and can wear off over time. Also, with some diseases, like measles, the disease itself can be deadly, so it’s better to avoid it altogether by getting vaccinated.


What Are Vaccines?: The History of Vaccination and Immunization


Vaccines are a vital part of modern healthcare, helping to protect people from deadly and debilitating diseases. Their history stretches back thousands of years, beginning with smallpox inoculations in ancient China. Over time, vaccines have continued to evolve and become more effective. Perhaps the most important development in vaccine history was the introduction of the first vaccines against common childhood diseases like measles and polio.

The history of vaccines is long and complicated, with many important milestones along the way. Around 200 years ago, Edward Jenner developed the first vaccines, which consisted of extracts from cowpox lesions on the udder or teat of cows.

At that time, people did not know how to prevent or treat infections, so when smallpox outbreaks occurred, many people died. During a smallpox outbreak in England in 1796, Jenner observed that milkmaids who had previously contracted cowpox (a mild infection caused by a related virus) did not contract smallpox. He theorized that perhaps the cowpox virus could “immunize” someone against smallpox and set out to test his theory.

In 1796, he inoculated an 8-year-old boy with cowpox virus (a related virus to smallpox) and then exposed him to smallpox. The boy did not develop smallpox. Jenner called this process “vaccination” after the Latin word for cow, vacca.

Vaccines, also known as immunizations, are one of the great success stories in public health. They are products that help protect against infections by “teaching” the immune system to recognize and fight specific types of germs. They are usually given by injection (shot), but some can be given orally (by mouth) or nasally (sprayed into the nose). Vaccines also come in a variety of types.

Types of Vaccines


A vaccine is a biological preparation that provides immune protection against infections. Vaccines contain antigens, which are substances that induce an immune response. When a person is vaccinated, they are exposed to the antigens in the vaccine, which causes their immune system to produce antibodies. The antibodies help protect the person from infection by the disease that the vaccine is meant to prevent.

There are four types of vaccines:

  • live attenuated
  • inactivated
  • toxoid
  • subunit



Live Attenuated Vaccines


Live attenuated vaccines (LAV) use a weakened form of the virus or bacteria to provoke an immune response. LAVs are used to vaccinate against many diseases, such as measles, mumps, rubella, and influenza. How does a LAV work?

When a person is vaccinated with a LAV, they are injected with the weakened form of the virus or bacterium. This weakened form can replicate inside the body but isn’t strong enough to cause disease. As it replicates, it creates an immune response in the body and helps the person develop immunity to the disease. The viruses or bacteria in LAVs are often attenuated (weakened).


Inactivated Vaccines


Inactivated vaccines use dead viruses or bacteria to stimulate immunity. These vaccines use viruses, bacteria, or other organisms that have been grown in a laboratory and then killed before they are used to immunize someone. Inactivated vaccines are sometimes called “killed” or “whole-cell” vaccines.

The process of making an inactivated vaccine usually starts with selecting the viruses, bacteria, or other organisms to be used in the vaccine. The next step is to grow the selected organism in large quantities in the laboratory. After the organism has been grown, it is exposed to a special kind of heat or chemicals that kills it. Once it is killed, it can’t cause infection anymore. When these weakened viruses or dead bacterial particles enter our body, our immune system recognizes them as ‘foreign invaders’.


Toxoid Vaccines


Toxoid vaccines use toxins produced by bacteria to trigger immunity. This vaccine contains inactivated toxins. Toxins are poisonous substances produced by bacteria or other organisms. Inactivating the toxin makes it safe to use in a vaccine. When you receive a toxoid vaccine, your body produces immunity (protection) against the disease caused by bacteria or other organisms.

Toxoid vaccines are used to protect against diphtheria and tetanus. Diphtheria and tetanus are serious diseases caused by bacterial toxins. The diphtheria toxoid vaccine is usually given as part of the DTaP vaccination (diphtheria, tetanus, and pertussis). The DTaP vaccination is given to children under seven years of age.


Subunit Vaccines

Subunit vaccines use only pieces of the virus or bacteria to generate immunity. A subunit vaccine is made from only a part of the virus or bacterium. For example, some flu vaccines are made from just one protein from the flu virus. These vaccines can be made more quickly. They also might be easier to make if there is a shortage of the virus or bacterium.

Subunit vaccines usually work by causing the body to produce immunity against the part of the virus or bacterium that is used to make the vaccine. This type of immunity is called cellular immunity because it involves cells in your body, such as T cells and B cells. Cellular immunity protects you from disease by attacking viruses or bacteria inside your body.

When you get a subunit vaccine, your body recognizes the antigen as foreign and produces antibodies. If you ever encounter a real virus or bacterium, your body will already have some antibodies ready to fight.


What is the Immune System?


The immune system is the body’s defense against infection. It is made up of many different cells and proteins that work together to fight off foreign invaders. Vaccines help to strengthen the immune system by providing it with exposure to antigens, which helps it to develop better ways of fighting off infections in the future. The immune system can be divided into two parts: innate immunity and adaptive immunity.

Innate Immunity


Innate immunity is the first line of defense against infection. It is present at birth and does not change over time. Innate immunity relies on special cells called phagocytes that engulf and destroy foreign invaders.

Adaptive Immunity


Adaptive immunity develops over time in response to infections or vaccination. It produces antibodies that specifically recognize and destroy particular antigens.

What is an Antigen?


Put simply, an antigen is any foreign substance that elicits an immune response in the body. Antigens can be viruses, bacteria, parasites, or anything else that the body perceives as a threat. When the body comes into contact with an antigen, it produces special proteins called antibodies to neutralize the threat. Antibodies are produced by white blood cells called lymphocytes. Each type of lymphocyte is specifically programmed to produce a different antibody, which allows them to target different types of antigens. So, antigens are substances that trigger an immune response.

What are Antibodies?


An antibody is a type of protein that is produced by the immune system in response to a foreign substance, such as a virus or bacteria. Antibodies are important in helping to destroy these harmful invaders and protect the body from disease. Each antibody is specific to a particular invader and will bind to it to neutralize it or mark it for destruction.


Why Are Vaccines Important for Public Health, Epidemiology, and Microbiology?


Vaccines are an important tool in the fight against the spread of disease. By immunizing people against illnesses, vaccines help to protect entire communities from outbreaks. When a person is immunized, their body produces antibodies that recognize and ward off specific infections. This process not only protects the immunized individual but also helps to prevent the spread of disease within a population. By vaccinating against common diseases, we can help to protect both individual and public health.

Public Health


While most vaccines are given to children, adults need to remain up-to-date on their immunizations as well. For example, the influenza vaccine is recommended for everyone over the age of six months. Immunizations not only protect the individual but also help to prevent the spread of disease to others, particularly those who are unable to receive vaccinations due to medical conditions. As a result, vaccines play a vital role in protecting public health.



They are also important for epidemiology, as they can be used to track and control outbreaks of disease. Vaccines help prevent epidemics, keep communities healthy and track disease spread. For example, when illnesses like measles or diphtheria outbreaks occur, researchers can track where the illness began and how it spread. This information can then be used to develop new vaccines and better ways to prevent disease outbreaks in the future.



Microbiology covers a wide range of topics, from the structure and function of microbial cells to the role of microorganisms in human disease. Vaccines are important for microbiology, as they can be used to study how diseases develop and spread. This is important for understanding disease development and progression.


Putting Vaccines and Public Health Together: What is Herd Immunity?


Herd immunity is a form of immunization that occurs when the immunization of a significant portion of a population (the “herd”) provides a measure of protection for individuals who have not developed immunity. It is achieved by protecting people who are unable to develop immunity, such as young children or immunocompromised individuals, by ensuring that there is a smaller pool of vulnerable individuals from disease spread. Herd immunity is particularly important in the control of infectious diseases.

Immunization of a significant proportion of the population can help to reduce the spread of disease, and can also help to protect those who are unable to develop immunity. However, herd immunity is not absolute and does not guarantee complete protection from disease. It is possible for immunized individuals to still contract and spread disease if they come into contact with a large enough number of susceptible individuals.

Additionally, herd immunity can be lost over time if immunization rates decline. This can lead to disease outbreaks among previously immunized populations. That is why vaccines are just part of the infectious disease prevention puzzle.

Kimberly Hazel

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