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How Do Vaccines Work?

How Do Vaccines Work?

Since their creation, vaccines have saved millions of people from disease. In fact, vaccines are arguably the most important advancement in medical science, especially when it comes to maintaining good health.

Despite this, there remains a lot of misinformation about vaccines. In order to clear things up, we will be answering the question of “how do vaccines prevent disease?” to better understand why this is so important to our health.

How Do Vaccines Prevent Disease?

What is a vaccine?

In order to answer the question of “how do vaccines prevent disease?” we first need to talk about what a vaccine is.

A vaccine is a type of medicine that boosts a person’s immune system to protect the body against diseases. These are usually injected directly into the body, but some vaccines can be taken orally, and a few vaccines can be applied directly to the skin.

Vaccines work by training the body’s immune system to fight against various diseases. You can think of vaccines as a training mission for the immune system.

Vaccines do this by imitating an infection, which causes the immune system to respond in kind. This way, the immune system can safely learn how to fight off infection and remembers it for the future.

This means that if a vaccinated person gets exposed to a certain disease, their body knows how to respond, and can fight off the disease before anything bad can happen.

What are vaccines made of?

Scientists have developed different ways to create vaccines depending on what disease it is effective against.

Here are the different types of vaccines available:

Live attenuated vaccines

Live attenuated vaccines are made of a weakened or asymptomatic form of the virus or bacteria. Since it is already a weak form of the infection, it can not cause any harmful symptoms, and it will not spread any illness.

However, live attenuated vaccines are not given to people with weakened immune systems or those diagnosed with HIV or similar health problems. This is because even if it is a milder form of the disease, a person with a weakened immune system might not be able to fight it off.

But for most healthy individuals, live attenuated vaccines are perfectly safe.

Inactivated vaccines

Inactivated vaccines are essentially “dead” viruses or bacteria that is injected into the body. Even if the disease is already inactivated, the immune system still responds to the infection, and can still learn how to fight it off.

Compared to live attenuated vaccines however, inactivated vaccines would need several booster shots for a person to develop full immunity. This is because the dead remnants of the disease do not exactly behave like live disease.

So the body needs the booster shots to “train” the immune system more.

Subunit/conjugate vaccines

Subunit or conjugate vaccines differ in that they use specific proteins or carbohydrates of the disease. This means that there is almost no risk of using subunit or conjugate vaccines since it is not the actual disease itself.

When injected into the body, the immune system treats the vaccine as infection and can react in kind.

The drawback to subunit/conjugate vaccines is that identifying the specific chemicals to isolate from the disease is not always easy or even possible. This is why these types of vaccines are only applicable for certain diseases and not all of them.

Toxoid vaccines

Toxoid vaccines are similar to inactivated vaccines in that they use deactivated toxins to train the body’s immune system.

The immune system can then learn how to fight off the actual infection based on these deactivated toxins alone.

DNA vaccines

DNA vaccines are currently still being tested and are an experimental form of vaccines. These vaccines use DNA strands from the disease in order to teach the immune system how to develop a resistance to it.

The great thing about DNA vaccines is that they are very effective, and also cheap to produce. But at the moment, they are still being tested and studied for human use.

Recombinant Vector Vaccines

These types of vaccines are similar to DNA vaccines in that they use the DNA of a weakened virus or bacteria and “dress” it in the DNA of a more dangerous disease.

This means that the immune system can learn how to deal with both of those diseases at the same time. However, just like DNA vaccines, these are still in the experimental stages and still being studied by scientists.

What Diseases Can Vaccines Help Prevent?

There are numerous serious diseases that can be prevented with a simple vaccination. These include:

  • Flu
  • Measles
  • Chickenpox
  • Polio
  • Tetanus
  • Hepatitis B
  • Mumps
  • Haemophilus Influenzae Type B
  • Meningococcal Disease
  • Pneumococcal Disease

Consult your doctor regarding vaccines for your children or yourself.

How Safe Are Vaccines?

It is possible for certain vaccines to have side-effects in some people. However, the chances of it happening are extremely slim, and the benefits of being vaccinated outweigh any of the possible risks.

Some people mistakenly believe that vaccines cause autism, but in reality, we do not even know the cause of autism. Plus, autism has been found to start in the womb, so it is impossible for vaccines to cause autism.

Additionally, vaccines should only be given by doctors and should be following a vaccination schedule. This helps make sure that the person being vaccinated will not experience any harmful side effects from the vaccine.

Vaccines Also Benefit Those Who Are Not Yet Vaccinated

Not everyone can get vaccinated. People who have immune problems and newborn babies, in particular, cannot be vaccinated. This is where the concept of herd immunity comes in.

Herd immunity happens when a large amount of the population is immune to a certain type of disease. Since most people are immune, they also will not pass the virus to those who have not yet been vaccinated, essentially “passing on” their immunity to others.

This is very important in babies, whose immune systems are not yet well-developed, and for people with serious illnesses who cannot be vaccinated.

People with HIV or AIDS also greatly benefit from herd immunity since they themselves cannot be vaccinated against certain diseases.

This is why it is important to get complete vaccinations to not just protect yourself, but others as well.


Learn more about Drugs here.

Hello Health Group does not provide medical advice, diagnosis or treatment.


To vaccinate or not to vaccinate? Searching for a verdict in the vaccination debate – Science in the News, http://sitn.hms.harvard.edu/flash/2016/to-vaccinate-or-not-to-vaccinate-searching-for-a-verdict-in-the-vaccination-debate/, Accessed July 9 2020

What you need to know about: vaccines – Harvard Health, https://www.health.harvard.edu/staying-healthy/what-you-need-to-know-about-vaccines, Accessed July 9 2020

Why Cleveland Clinic Supports Vaccination – Health Essentials from Cleveland Clinic, https://health.clevelandclinic.org/why-cleveland-clinic-supports-vaccination-infographic/, Accessed July 9 2020

How Vaccines Work | PublicHealth.org, https://www.publichealth.org/public-awareness/understanding-vaccines/vaccines-work/, Accessed July 9 2020

How Vaccines Work, https://www.cdc.gov/vaccines/hcp/conversations/downloads/vacsafe-understand-color-office.pdf, Accessed July 9 2020

How Do Vaccines Work? | Live Science, https://www.livescience.com/32617-how-do-vaccines-work.html, Accessed July 9 2020

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Medically reviewed by Hello Doctor Medical Panel
Written by Jan Alwyn Batara
Updated Jul 11, 2020