News from CRIS: Vaccine Safety - COVID-19 Vaccine

January 26, 2021

What are vaccines?

A vaccine is a biological preparation designed to provide our body with active immunity to particular infectious pathogens when appropriately administered.

Vaccines stimulate immunological memory. Once we've received a vaccine, our body's immune system can recall a specific pathogen's identity, even years later, and effectively fight the pathogen.
 
You can learn more about how vaccines work, ingredients in vaccines, and general comments about their safety in our previous blog posts (1,2).

What type of vaccine is the COVID-19 vaccine?

Due to the urgency to develop a vaccine against COVID-19, various approaches have been employed, both established and novel, by numerous pharmaceutical companies. To date, two vaccines have been approved by the US Food and Drug Administration. Both of these approved COVID-19 vaccines have capitalized on a novel strategy to develop what is termed a messenger ribonucleic acid (mRNA) vaccine.
 
An mRNA vaccine provides instructions to our cells to produce harmless proteins that trigger an immune response.

How do the COVID-19 mRNA vaccines work?

Like most viruses, the virion of the SARS-CoV-2 virus that causes COVID-19 contains a ribonucleic acid (RNA) center coated in an envelope of protein and fat.
 
Once a virus enters a host (our body), the protein binds to the host's healthy cells, facilitating the entry of viral RNA into host cells and forces the healthy cells to produce copies of the virus. When this occurs, we have an infection.
 
As we've discussed in a prior blog post, once we're infected, our body's white blood cells multiply to stop the virus, but that takes time (1). While most healthy individuals successfully fight off COVID-19 infections, many individuals with underlying health concerns cannot fight off the infection, causing them to succumb to the disease.
 
We know our body’s immune system can destroy the virus if given enough time. The COVID-19 mRNA vaccine primes our body to respond more effectively by expanding those cells that can recognize and then destroy the SARS-CoV-2 virus.
 
Unlike attenuated vaccines that use weakened pathogens to prime our immune system to fight infection, the COVID-19 mRNA vaccines do NOT contain any SARS-CoV-2 virus.
 
Instead, they contain mRNA that gives our cells instructions to make a harmless-to-us piece of protein that’s the same as the protein present in the SARS-CoV-2 virus. The protein then teaches our immune cells to identify and combat the SARS-CoV-2 virus.
 
Once our body makes the harmless-to-us protein, our body breaks down the instructions (mRNA) and eliminates the instructions from our body, leaving our body with the protein.
 
Next, our body’s immune system will recognize the protein as foreign (i.e., doesn’t belong to us) and develop an immune response including antibodies to destroy the protein. As we’ve covered in a prior post, our body’s immune system remembers how to fight and eliminate unwanted pathogens.
 
Now that our body’s immune system knows how to destroy the protein found on the SARS-CoV-2 virus that causes COVID-19 infections, if we are exposed to COVID-19, our body has been trained to identify and destroy the protein that keeps the SARS-CoV-2 virus viable and thus protect us from the virus (1).

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Read the entire blog post at: https://www.canr.msu.edu/news/vaccine-safety-covid-19-vaccine.