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COVID Vaccines

Which Vaccines are Available?

What vaccines are available in the United States?

There are three different vaccines available in the United States: 

  • Pfizer-BioNTech
  • Moderna
  • Johnson & Johnson's Janssen

All three vaccines are effective at reducing the spread and severity of a COVID-19 infection, and are extremely unlikely to cause adverse effects. Currently the Center for Diseases and Control is recommending the Pfizer-BioNTech and Moderna Vaccines over the Johnson & Johnson vaccines for most individuals, and you can read more about the differences in these vaccines here, or check out the chart below. 


The above information is pulled from the Centers for Disease Control and Prevention (CDC) which is a national public health agency in the United States that strives to keep American citizens healthy by developing mechanisms for preventing disease, injury, and disability.  The CDC is not a partisan agency, but rather it is responsible to its mission of protecting public health for the citizens of the United States. The CDC is a great resource for learning more about COVID-19 and other public health issues. 

What's in the Vaccine

What's in the Vaccines: 

mRNA Vaccines:

Both the Pfizer-BioNTech and Moderna are mRNA Vaccines. They contain one active ingredient, mRNA, and a handful of inactive ingredients including lipids, sugars, and salts. 

  • mRNA stands for messenger RNA, and it directs the cell to build proteins that will train the cells immune response to fight the COVID-19 virus. You can read more about how mRNA works below. 
  • Lipids, or fats, provide a shell around the mRNA (think of them as organic packaging)
  • Sugar helps maintain the shape and structure of the mRNA when the vaccine freezes
  • Salts and acids help the vaccine match your bodies natural acidity levels
  • The vaccines do not contain any coronavirus in them 

Viral Vector Vaccines:

The Johnson & Johnson's Janssen vaccine is a viral vector vaccine. It contains "a harmless version of a virus unrelated to the COVID-19 virus,"  and a handful of other inactive ingredients including lipids, sugars, salts, and acid stabilizers (CDC, 2022)

  • The harmless virus in the J & J vaccine directs the cell to build proteins that will train the cells immune response to fight the COVID-19 virus. It plays a role that is similar to the role that the mRNA plays in the mRNA vaccines.
  • The J&J vaccine also includes lipids, sugars, salts, and acid stabilizers which help to stabilize the vaccine molecules while they're, shipped, and stored. You can read more about the specific roles these provide above under the mRNA section.


You can find a full list of the ingredients in each of the vaccines available in the United States here:


What is NOT in the vaccines?

None of the vaccines approved for use in the United States include any of the following ingredients (CDC, 2022)

  • No preservatives (including no mercury)
  • No antibiotics 
  • No tissues (no aborted fetal cells, gelatin, or other materials from any animal)
  • No food proteins (including no eggs or egg products)
  • No metals/ Nor micro-electronics
  • No latex


What's mRNA and what's it got to do with vaccines? 

To understand how mRNA vaccines work, let's start by learning a little bit about the COVID-19 Virus and human cells. 

What's a Virus? 

A virus is a collection of genetic code (RNA) contained inside a protein coat. The outside of the virus has little protrusions that are called spike proteins. (Protein is just a fancy name for organic molecules, the stuff we're all made out of). 

On a coronavirus, the Spike protein's job is to help the coronavirus enter your cell (It's like a doorman to the cell). The spike protein itself is not dangerous (only the RNA inside the protein coat on a coronavirus is dangerous). 

Spike protein's are important to vaccines because they have a unique structure that your immune system is able to identify. In some ways a spike protein is like a criminals fingerprint, and your immune system is a detective that is able to read fingerprints and then pursue criminals. 

What's mRNA? 

mRNA, or messenger RNA is single strand RNA molecule that can be read by your cell to make proteins. It is referred to as a messenger because it delivers protein building plans to the parts of your cell that build proteins. If you think of your cell as a large construction site, your cells DNA would be the equivalent of the construction master plans. DNA is stored in the nucleus of the cell (the equivalent of a central office on a construction site), and the DNA never leaves the main office. However, when workers have to go outside and build, they take copies of the relevant pages of the original master plan onto the construction site to go build. mRNA in our cells is the equivalent of these copies. mRNA contains the directions for making proteins, the building blocks of the body. Every single day our cells send mRNA from the nucleus to the cytoplasm where it is provides the directions for making proteins through a process called translation. Soon after translation (within minuets to hours) the mRNA in human cells starts breaking apart and the materials in them get recycled by your cell. 



What do mRNA Vaccines do? 

A mRNA vaccine reduces the likelihood of severe COVID cases by teaching and preparing your immune system to fight future COVID-19 infections.  The mRNA in the vaccines is the same type of molecule that comes from your cell's nucleus, which is already in your cells; the only difference is that it comes from the vaccine. The mRNA in the vaccine contains the instructions to make a protein that is very similar to the harmless Spike proteins on the COVID-19 virus. Once in your cell, your cell translates the mRNA, which means your cells make a protein that is very similar to the harmless Spike Proteins on the COVID-19 virus. When your immune system notices these new imitation Spike proteins, they go on the attack, and start breaking down these proteins. During this process they also learn to quickly identify the imitation spike proteins, and they build up armies of specialize "antibodies" that are trained specifically to attack that type of protein. As your cells are attacking these proteins and building up armies of antibodies, it is common to feel tired. This is because there is a lot of work going on in our cells. 


What happens when you're exposed to COVID-19 after receiving an mRNA vaccine? 

If you are exposed to the COVID-19 virus after receiving a mRNA vaccine, you are in luck, because your body will be better prepared to fight it than it would have been if you hadn't had the vaccine. When the COVID-19 virus enters your cells, the armies of antibodies that were built in response to the imitation Spike proteins will identify the COVID-19 virus Spike proteins, and will imediatley start to fight the COVID-19 virus. When this happens you still may get a little sick or be more tired than normal, but you are much more likely to avoid serious illness from COVID-19 than you would have been with out the immune system boost provoked by the vaccine. 


Because viruses evolve, and because antibodies don't last for forever, you may occasionally need to get a booster vaccine shot, so that you can make sure your body is up to date with the most recent model of imitation Spike proteins.

In summary, the mRNA vaccine is an effective and safe way to expose you to the Spike proteins found on COVID-19 viruses, with out actually exposing you to the real coronavirus, so that your body can build up antibodies that are specialized to attack the COVID-19 virus in case it ever encounters the real virus. 

You can read more about mRNA following links: 

Understanding mRNA COVID-19 Vaccines

11 Things to Know About mRNA Vaccines for COVID-19

Different types of COVID-19 vaccines: How They Work.

Can mRNA Vaccines Alter A Person's DNA?

What are mRNA vaccines and how do they work?