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Comparing the three COVID-19 vaccines

Posted at 10:45 AM, Mar 02, 2021
and last updated 2021-03-02 11:45:20-05

OMAHA, Neb. (KMTV) — Johnson & Johnson's vaccine joins the Pfizer and Moderna shots now available on the market, but what are the differences between the three vaccines?

3 News Now reporter Kent Luetzen breaks down the science.

The COVID-19 vaccine: biopharmaceuticals sound complicated and overwhelmingly technical, but doctors say understanding the science in the shots may help people understand the differences in the available vaccines.

All pathogens that cause infectious diseases like COVID-19 have an associated antigen; the antigen is what activates our immune system to fight that virus.

The Moderna, Pfizer and Johnson & Johnson vaccines target a part of the virus that cause COVID-19 called the "spike protein." The spike protein is what allows the coronavirus virus to enter our cells and multiply.

“Sometimes people think it's like a bar code in the grocery store where if you get the vaccine, it is for that brand of applesauce. The reality is your body does not look at it that way, when your body responds to the bar code of the applesauce, the lesson is not only, hey, that's really great applesauce. Part of the lesson is applesauce is good. And so to a certain extent, your body learns to look for applesauce, not just that brand, and vaccines are similar,” said Dr. David Brett-Major with Internal Medicine at UNMC.

Johnson & Johnson's vaccine is now the third COVID-19 vaccine approved for emergency authorization use by the FDA. Why did it take Johnson & Johnson take so much longer to develop a vaccine compared to Pfizer and Moderna?

The technology behind Pfizer and Moderna, mRNA or messenger RNA, has been researched for more than a decade, but this is the first vaccine where the biotech worked.

To give the body that antigen boost, scientists made Johnson & Johnson's vaccine by taking a small amount of genetic material that is the code for the novel coronavirus. They combine it with a weakened version of a common cold virus called adenovirus. That combination can enter cells but won't replicate and make us sick. Johnson & Johnson's vaccine approach isn't new.

With mRNA, scientists quickly identify a genetic code to make the antigen protein specific to the disease. The mRNA vaccine delivers this code to tell our body to make the antigen itself. That's what prompts an immune response.

Vaccines made with mRNA are relatively easy and quick to produce compared to traditional vaccine-making, which is partially why Moderna and Pfizer were first to the finish line.

The difference between the technologies also impacts storing and transport.

The mRNA vaccines have to be kept very cold and have to be used just days after thawing out. The Johnson & Johnson one is okay at refrigerator temperatures for up to three months.

With side effects, both the mRNA vaccines have, on rare occasions, caused anaphylaxis, a severe and sometimes life-threatening allergic reaction. The Johnson & Johnson vaccine data hasn't shown that to date.

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