evidence: You asked, we answered: Do the COVID-19 vaccines contain tromethamine, luciferase or graphene oxide? [...] Yes, Pfizer, Moderna and Johnson & Johnson (Janssen) provided detailed information about the ingredients in their COVID-19 vaccines to the U.S. Food and Drug Administration (FDA). Read the information provided to the FDA. The most important ingredient in both the Pfizer and Moderna vaccines is mRNA. The mRNA tells your cells how to make a protein from the coronavirus. Once your body knows how to make the protein, it can recognize COVID-19 and fight it. Learn more about how mRNA vaccines work.