News from CRIS: Vaccine Safety - J&J Vaccine

March 9, 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 immune responses and build 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).
 

How does the newest vaccine work?

Unlike the other two vaccines available, the newest vaccine by Janssen (J&J) does not use the latest mRNA technology to build our system’s immunity. Rather, the J&J vaccines use a more traditional mechanism to trigger an immune response.
 
The J&J vaccine is a recombinant vaccine (1,2). It contains a safe adenovirus vector that has been engineered to make a harmless to us version of the spike protein found on the SARS-CoV-2 virus. By doing so, it serves as a dummy to train our immune system to better combat the SARS-CoV-2 virus (1).
 
As we know, 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.
 
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 the SARS-CoV-2 virus infection, 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 J&J vaccine primes our body to respond more effectively by expanding those immune cells (white blood cells) that can recognize and then destroy the SARS-CoV-2 virus.
 
Unlike the Pfizer-BioNTech and Moderna vaccines, the J&J vaccine does not use mRNA. Instead, it uses an adenovirus vector to get the needed instructions to our cells.
 
The adenovirus vector is essentially a harmless cold virus that cannot replicate itself in our body nor can it cause disease. Therefore, it has been used as a platform for a variety of vaccines. Its safety has been demonstrated by several clinical studies with more than 100,000 participants (1).
 
The adenovirus vector in the J&J vaccine has been engineered 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.
 
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 that bind to the protein and eliminate the pathogen. 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 has been trained and remembers how to identify the protein found on the SARS-CoV-2 virus that causes COVID-19, if we are exposed to the SARS-CoV-2 virus, our body will effectively produce antibodies that can binds to the protein on the SARS-CoV-2 virus and eliminate the virus thus protecting us from the virus (1). 

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