Types of Vaccines: The 6 Useful Types of Vaccines

Many types of vaccines are included in vaccination schedules

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There are different types of vaccines targeted against different diseases. Some are traditional types of vaccines that have existed for many years. Others are modern types that have been designed to respond to emerging challenges.

Their different types notwithstanding, vaccines have collectively averted many disease outbreaks in the world today. They have contributed to disease prevention much more than any other public health efforts.

Different types of vaccines are administered in different ways
A Patient Receiving Vaccine Injection which is An Delivery Method for Many Types of Vaccines (Source: Freepik Images)

We owe a lot of gratitude to the scientists who work tirelessly away from the public eye to discover them.  We need to put politics aside and embrace vaccines to continue keeping the world a safe place for our generation and generations to come.

What is a vaccine?

A vaccine is a substance that is made from a disease-causing antigen or related products. The vaccine stimulates your immune system to produce among other immune products, the antibodies that confer protection against the immunizing agent.

In other words, a vaccine is used to enhance your natural immunity to work smarter against foreign antigens. We train the immune system on how to decisively deal with foreign antigens within a very short time by administering a vaccine. Vaccines are administered through the process of vaccination.

How do vaccines work?

We now know that vaccines are made of the same organisms or parts of the organisms that they protect against. We shall partly explain how vaccines work by the use of an analogy.

An Analogy of Vaccines

As always, we like using a relevant analogy that can help you grasp the concept in the easiest way possible. Here we go:

For a country to stay safe from external and internal security threats, such a country invests in its defense forces. The investment could mean training the army, equipping them well, and any other training that tries to imagine the various types of threats that can emanate.

In the same way, administering the various types of vaccines raised against specific microorganisms/antigens trains your immune system. It is trained and keeps a memory of the vaccines it has been exposed to.

So, when the real disease comes, the already prepared ‘army’ in form of antibodies and other memory cells of the immune system will fight for you and win against the disease. This win will mean that you remain healthy. That’s what makes vaccines important.

Types of Vaccines

We have various types of vaccines in the world today. Some consist of the whole alive or killed organisms while others consist of parts or products of the organisms. Let’s now discuss in detail the 6 most useful types of vaccines in the world today:

1. Live-attenuated Vaccines

Live-attenuated vaccines are made of weakened microorganisms that cause disease. That means that the vaccine that one is given as a shot is an alive germ. However, scientists alter the structure of this germ so its ability to cause disease has been removed.

Nevertheless, your immune system still views the weakened germ in the vaccine as a foreign antigen that can induce an immune response (Antibodies + other protective cells). The attenuation (Weakening) of the germs is done by several passages through various biological systems until the germs lose their virulence (Ability to cause disease).

The advantage of these vaccines is that just 1 or 2 doses can protect you for life. That means you can do without boosters and maintain the initial protection that was conferred by the first and/or second dose of the live-attenuated vaccine.

The disadvantage of live-attenuated vaccines is that they can revert to the original dangerous form when not handled well. Some of the mishandling may include breaking the cold chain in their storage from manufacturing to administration.

If your immune system is weak for whatever reason, then live-attenuated vaccines are not good for you. They can be dangerous. Therefore, live-attenuated are nearly always contraindicated for people suffering from HIV/AIDS, cancer, pregnancy, and transplant patients whose immune systems have been suppressed.

Examples of live-attenuated vaccines in use today include the combined vaccine of Measles + Mumps + Rubella (MMR), Yellow fever vaccine, Smallpox vaccine, Rotavirus vaccine, and Chickenpox vaccine among others.

2. Inactivated Vaccines

Inactivated vaccines are also called killed vaccines. In these vaccines, the whole microorganisms are killed using various methods that include the use of chemicals, heat, and irradiation.

These vaccines alongside the live-attenuated vaccines are the traditional types of vaccines that have existed for a very long. When you’re given this kind of vaccine, it will be very because it can revert to the disease-causing version.

Types of vaccines available include oral polio vaccine
A doctor administering an oral polio vaccine to a child (Image source: Freepik)

But its protection is relatively short-lived compared to the live-attenuated vaccines. This type of vaccine, therefore, requires booster shots to keep up the protection in your body.

Examples of inactivated vaccines in use today are hepatitis A, rabies, some flu vaccines, and polio vaccine (Salk vaccine) among others.

3. Messenger RNA (mRNA) Vaccines

These vaccines have the mRNA of some proteins known to be highly immunogenic (Can induce a strong immune response). In the case of COVID-19, for instance, scientists identified the spike proteins of SARS-coV-2 as highly immunogenic.

They then package the mRNA of the virus into a modified adenovirus and injected people to protect them against COVID-19. The mRNA is the genetic material that has been transcribed from DNA and is just about to be translated into proteins.

mRNA COVID-19 Vaccine is one on the types of vaccines in use today
This photo shows how the mRNA COVID-19 Vaccine Works Once Delivered to the Body

The advantage is that it takes a shorter time to make such vaccines. In addition, this type of vaccine is very safe as it cannot cause disease by reverting to the original disease-causing organism.

4. Viral Vector Vaccines

Viral vector vaccines are those that use viral vector technology to deliver the vaccines to the desired part of your body. In this case, a modified virus would have been used as a vessel of delivery of the antigens (Vaccine). Some of the modified viruses that can be used as vectors include adenovirus, influenza virus, and measles virus among others.

Examples of diseases that use this technology in vaccination include COVID-19, HIV/AIDS, Zika, and Flu among others. The use of virus technology is pegged on the fact that for a virus to replicate, it must be inside the cells.

Viral Vector Vaccine is one of the types of vaccines in use today
Viral Vector Vaccine for SARS-CoV-2 for COVID-19 vaccination – types of vaccines (Unsplash photos)

Therefore, the modified virus that is packaged with the antigens (Vaccines) is delivered inside the desired cells by the viral vector and then expressed later by the cells as proteins.

The immune system then mounts an immune response which creates protective antibodies against the expressed proteins conferring protection in your body. These types of vaccines are very safe.

5. Subunit Vaccines

Subunit vaccines are vaccines that use some parts of the microorganism and not the whole organism. They may target some surface proteins, capsids, or some glycoproteins (Sugar + Proteins) on the plasma membrane of the microorganisms. Recombinant and conjugated vaccines fall under this category as well.

These vaccines are very safe because they cannot revert to the microorganisms that cause disease. However, their immunogenicity (Ability to protect) needs boosters after some time to continue protecting you.

Examples of diseases/microorganisms in which you can be protected against using this type of vaccine are pneumococcal disease, meningococcal disease, Haemophilus influenza type b, whooping cough, hepatitis B, and human papillomavirus among others.

6. Toxoid Vaccines

In some infections, the disease is caused by some products (Toxins) produced by the microorganism and not the organism itself. Therefore, when it comes to making vaccines, scientists target the toxins and not the whole germ. Toxins that are administered as vaccines are called toxoid vaccines.

Examples of diseases against which we are protected through toxoid vaccines include Diphtheria and Tetanus. Such vaccines may need boosters from time to time as they may not provide life-long protection to you.


The six types of vaccines are live-attenuated vaccines, Inactivated vaccines, Messenger RNA (mRNA) vaccines, Viral vector vaccines, Subunit vaccines, and Toxoid vaccines. Each of the 6 most useful types of vaccines is designed for a specific microorganism.

Therefore, you can only use the type that is available for a specific disease. There are a few examples of vaccines that exist in more than one form. An example is a vaccine for poliomyelitis that exists as a live-attenuated vaccine and as an inactivated vaccine.  

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8 thoughts on “Types of Vaccines: The 6 Useful Types of Vaccines

  1. Dr Mutai Brian says:

    Very informative,, I just enjoy reading this article and gaining more knowledge,, thanks Sir 🙏

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