It can be intimidating to try to read through ingredient lists for any vaccine or medicine. They are complex medications, which is why they are so well-tested.
The most important ingredients in the Pfizer and Moderna vaccines are mRNA. This is what tells your cells how to fight COVID if you get exposed. mRNA starts to break down within a few hours of injection, and once it teaches your body how to fight the virus, it dissolves completely.
The Johnson & Johnson vaccine’s most important ingredient is an adenovirus, which acts like a delivery vehicle to teach your body what the COVID protein looks like. This adenovirus can‘t reproduce though, so it can‘t cause an infection.
After that, the vaccines contain a variety of fats, salts, and other ingredients to help your body use the blueprints correctly.
Video uploaded 12/8/20
SOURCE: https://www.nebraskamed.com/COVID/you-asked-we-answered-are-covid-19-vaccine-ingredients-public (Nebraska Medicine)