"COVID vaccine biopharmaceuticals." Sounds complicated. Overwhelmingly technical. But doctors tell Newsy understanding the science in the shots may help people feel more confident in picking a COVID vaccine thats right for them. Dr. John Hammer, infectious disease specialist at Rose Medical Center: "We'll have some good options for preventing severe illness hopefully rolling out across the population over the course of the next several months."All pathogens that cause infectious diseases like COVID-19 have an associated antigen, and the antigen is what activates our immune system to fight that virus. Moderna, Pfizer and Johnson & Johnsons vaccines target a part of the virus that causes COVID-19 called the spike protein. The spike protein is what allows the coronavirus virus to enter our cells and multiply."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," said Dr. David Brett-Major, an internal medicine and infectious diseases physician at the University of Nebraska Medical Center. "When your body responds to the bar code of the applesauce, the lesson is not only, hey, that's a 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."To give the body that antigen boost, scientists made Johnson & Johnsons vaccine by taking a small amount of genetic material that codes for the novel coronavirus. They combine it with a weakened version of a common cold virus called adenovirus. That combination can enter cells but wont replicate and make us sick. J&J's vaccine approach isnt new. "It has been used in multiple vaccines and multiple vaccine platforms in the past, including their Ebola vaccine and others," Hammer said.The tech 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. 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. Thats what prompts an immune response. MRNA is 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 MRNA vaccines have to be kept very cold and have to be used just days after thawing out.The J&J one is OK at refrigerator temperatures for up to 3 months.And with side effects, both the MRNA vaccines have, on rare occasions, caused anaphylaxis, a severe and sometimes life-threatening allergic reaction. J&J vaccine data hasnt shown that to date.