What are the actual ingredients in COVID-19 vaccines according to CDC?
Executive summary
The Centers for Disease Control and Prevention directs readers to each COVID-19 vaccine’s FDA fact sheet or package insert for the definitive list of ingredients and notes that those documents contain the full ingredient disclosures [1] [2]. Public summaries compiled by state and health outlets show mRNA vaccines (Moderna/Spikevax and Pfizer/Comirnaty) list nucleic acid plus lipid nanoparticles and stabilizers, while viral‑vector vaccines (Janssen/Johnson & Johnson) list a modified adenovirus and common excipients—details that the CDC advises consulting in the product information [3] [4] [5].
1. What the CDC says and where it points readers
The CDC’s COVID‑19 vaccine guidance repeatedly instructs clinicians and the public to consult vaccine‑specific package inserts, FDA fact sheets, or the U.S. Vaccine Product Information for a full, authoritative list of ingredients, storage and handling, and administration details rather than relying on summaries alone [1] [2] [5].
2. Ingredients listed for Moderna (Spikevax) in public summaries
State and public health summaries that cite CDC and manufacturer material list the Moderna vaccine ingredients as messenger RNA (mRNA) encoding spike protein encapsulated in lipids (including SM‑102, polyethylene glycol [PEG] 2000 dimyristoyl glycerol [DMG], cholesterol, and DSPC), plus tromethamine and tromethamine hydrochloride, acetic acid, sodium acetate trihydrate, and sucrose as stabilizers and pH buffers—information provided by Moderna’s package documentation and referenced by public resources [3] [6].
3. Ingredients reported for Pfizer‑BioNTech (Comirnaty)
Public reporting and FDA disclosure letters list Pfizer‑BioNTech’s vaccine as mRNA in lipid nanoparticles with specific lipids and polyethylene glycol components; Reuters and other repositories reference the FDA fact sheets and CDC pages for the exact ingredient lists and usage instructions, and readers are directed to those official sources for the precise, updated enumerations [4] [7].
4. Ingredients in viral‑vector vaccines (Johnson & Johnson/Janssen)
Summaries that aggregate CDC and manufacturer information identify the Janssen vaccine as a recombinant, replication‑incompetent adenovirus type 26 vector expressing SARS‑CoV‑2 spike protein, with excipients such as citric acid monohydrate, trisodium citrate dihydrate, ethanol, 2‑hydroxypropyl‑β‑cyclodextrin (HBCD), polysorbate‑80, and sodium chloride listed in the product information [3] [6].
5. What the CDC says about common vaccine excipients and safety context
The CDC provides general ingredient explanations—what adjuvants, stabilizers, preservatives, and residuals are and why they’re used—and stresses that modern vaccines include only necessary components to ensure safety and effectiveness; that context is summarized in CDC‑linked explainers and longstanding vaccine ingredient pages [8] [9].
6. Misinfo, exclusions, and explicit denials in fact‑checking
Multiple fact‑checks and CDC guidance counter circulating claims that COVID‑19 vaccines contain items like thimerosal, aluminum (for mRNA vaccines), or fetal tissue as ingredients; Reuters and other fact‑checks note those claims are false and point readers back to the ingredient lists in official fact sheets and package inserts [10] [7].
7. Limitations and how to verify exact formulations
The CDC and archived clinical guidance make clear that vaccine formulations, brand names, and authorized uses have evolved; for the precise, up‑to‑date ingredient list for any specific product and lot, the FDA fact sheet or the manufacturer’s package insert should be consulted directly—the CDC serves as a portal to those product information documents rather than printing exhaustive ingredient tables in every guidance document [1] [2] [5].