Pharmaceutical and biotech companies around the world are in hot pursuit to develop a safe and effective vaccine for COVID-19.

In fact there are about seven different kinds of vaccines in development which attempt to address the virus in different ways. In this multipart series, I’ll show you exactly how each one of these vaccines work.

First let’s look at a quick primer of how vaccines work in general.

See our daily COVID-19 vaccine development tracker where we track the development of the COVID-19 vaccine from every single manufacturer.

How Vaccines Work in General

Our bodies contain a highly sophisticated System for battling invaders, the immune system. It works so well it’s battles invaders for us day and night and we don’t even notice it .

There are however exceptions; pathogens that are more robust than the every day bug. It’s not necessarily that our bodies cannot produce immunity for these invaders but it may not be able to do it quicker than the invader can cause harm.

Vaccines are a clever solution to this problem. They take the pathogen either in a dead, weakened, or otherwise inert form and put them in our bodies where the immune system can learn to recognize it and develop antibodies to protect us from the moment the real pathogen crosses our path. Antibodies are a special kinds of structure the immune system produces that can identify specific pathogens like puzzle pieces fitting together.

Are Vaccines Safe?

By and large vaccination is extremely safe and effective. Vaccination has been one of the most successful inventions for global health and has lead to the eradication and near-eradication of many diseases which threaten humanity.

Vaccine Safety | Vaccine Safety | CDC
CDC’s Vaccine Safety website. Resources and information about the safety of specific vaccines, vaccine side effects, and vaccine safety research.

The Different Kinds of Vaccines

In this series, I’ll be using a set of videos and short descriptions for each vaccines. Over time, I'll update this article to link to individual articles talking about each kind of vaccine in depth.

Replicating and Non-replicating Viral Vectors

Viral vectors are molecular structures used to deliver genetic material into a cell. For a vaccine, a vector includes a genetic component of a given pathogen. Once the genetic material is delivered, the body can trigger an immune response without the genetic material actually causing any harm.

Check back later for our special article on how replicating and non-replicating viral vector vaccines work.


RNA Vaccines are also vector-based. RNA is like DNA but single-stranded. It is used to encode amino acides which are the building blocks of proteins. Antigens are the part of a pathogen for which our immune system can identify. Because antigens are proteins, the RNA in a vaccine can cause our cells to make the antigens without the pathogen, and subsequently the immune response to it.

Check back later for our special article on how RNA vaccines work.


An inactivated vaccine uses versions of the pathogen which are dead or otherwise treated to no longer have the ability to harm us. At the same time, the inactivated form needs to retain the properties which allow our immune system to identify and protect against it in preparation for the real pathogen coming into our bodies.

Check back later for our special article on how inactivated vaccines work.

Protein Subunit

A protein subunit is a protein which assembles on its own or with other proteins to create a "protein complex." Antigens, being proteins themselves can be introduced to the body in the form of a protein subunit without introducing other parts of the virus. This allows the immune system to create a response with antibodies ahead of the actual pathogen entering the body.

How a Protein Subunit Vaccine Works


DNA vaccines use a plasmid (a circular and redundant DNA structure) containing a DNA sequence which codes for an antigen the immune system can use to create antibodies.

How a COVID-19 DNA Vaccine Works

Live Attenuated Virus

Live viruses in a weakened (attenuated) state can be used to both prevent the virus from harming the host but still retain enough of its original properties to trigger an immune response.

Check back later for our special article on how live attenuated virus vaccines work.