Decoding Moderna’s Covid-19 Vaccine Ingredients

A closer look at the ingredient list for Moderna’s coronavirus vaccine reveals a simple product safe for human use.

Jesse Smith, MD
Medium Coronavirus Blog
4 min readDec 4, 2020



Recent reports found that Moderna’s mRNA-1273 vaccine is over 94% effective against Covid-19 infection. This news is a bright spot in what has been a dark and challenging year.

Now that the vaccine is set to be rolled out, let’s take a look at the ingredient list.

The Basics

Moderna’s mRNA-1273 is an mRNA vaccine made up of strands of RNA packed into lipid nanoparticles. These particles, when injected into the human body will fuse to the cell membrane of human cells and allow the mRNA to gain access to the machinery needed to translate it into viral proteins. Once these proteins are generated, they are packed by the native vesicles within our own cells and released outside of the cell.

Once the viral proteins are released our immune system has the opportunity to generate antibodies against them.

Lipid Nanoparticle Technology

If the mRNA is the “message” of the vaccine, the lipid nanoparticle is the “envelope.” Lipid nanoparticles are created in the image of our own cell membranes, allowing them to travel within our bodies and fuse with human cells.

The lipid wall of the mRNA-1273 vaccine is made up of four different compounds:

  • SM-102 — a proprietary phospholipid that makes up the basic structure of the nanoparticle wall
  • DSPC — another commercially available phospholipid that will aid in the nanoparticle wall structure
  • Cholesterol — native to all of our cell membranes, cholesterol helps to add fluidity or stiffness to a cell membrane depending on temperature. The addition of cholesterol will aid in the stability of the nanoparticle.
  • PEG-2000 DMG — a lipid fused to polyethylene glycol with aids in the formation of the nanoparticle


The mRNA component of Moderna’s vaccine provides the human body the blueprint to generate copies of specific coronavirus antigens that elicit an immune response.



Jesse Smith, MD
Medium Coronavirus Blog

Physician and molecular biologist. I write about science, medicine, vaccines and dogs…yes dogs.