The ingredients used in the mRNA vaccines developed by Pfizer and Moderna are simple. They contain mRNA, as well as lipids to ensure safe delivery of the mRNA that will initiate an immune response.
Ingredients of the Janssen COVID-19 vaccine include: recombinant, replication-incompetent adenovirus type 26 expressing the SARS-CoV-2 spike protein, citric acid monohydrate, trisodium citrate dihydrate, ethanol, 2-hydroxypropyl-β-cyclodextrin (HBCD), polysorbate-80, sodium chloride.
Although FDA approved adjuvants (aluminum salts) and preservatives (ethlymercury) have a history of safe use in vaccines, they were not used by Pfizer, Moderna or Janssen.
- Tromethamine in the vaccine for children ages 6 months - 11 years: Tromethamine (Tris) buffer replaced phosphate buffered saline (pbs) in both the vaccine authorized for children 6 months - 11 years and an additional formulation authorized for those 12 and older. The Tris buffer in the vaccine for those 6 months - 11 years, which is a very small amount at 0.15 mg, is an inactive ingredient and serves as a stabilizer used to aide in a simpler and longer storage period. This switch will allow for the Pfizer vaccine to be stored at normal refrigeration temperatures for up to 10 weeks, which may increase the vaccine’s availability to underserved areas. Contrary to claims on social media, it is not being used to reduce blood acid levels in patients. Tromethamine has been used safely as an ingredient in FDA approved vaccines, like Ebola Zaire, smallpox and dengue fever, as well as the FDA approved Moderna COVID-19 vaccine.