Home Technology news What are the ingredients in Pfizer’s Covid-19 vaccine?

What are the ingredients in Pfizer’s Covid-19 vaccine?



Facebook said on December 3 that it would delete messages containing false statements or conspiracy theories about what’s in the covid-19 vaccines that everyone relies on.

Faced with rumors suggesting that Bill Gates installed tracking microchips in the shots, or that the inoculations contain luciferase, a glowing chemical from fireflies whose name makes some people think of the devil, the company suggested that ‘it would control these claims by referring to the “official list of vaccine ingredients”.

What is actually on the official ingredient list? This week an old british woman became the first person outside of a trial to obtain the newly approved vaccine developed by Pfizer and BioNTech, and the United States could give the green light to the same inoculation as early as Thursday, December 10. Along with the regulatory measures of last week came the most detailed. further disclosures of the composition of the new vaccine.

Here is, for example, what the United States Food and Drug Administration says in Pfizer’s vaccine:

  • Active ingredient
    • Modified nucleoside messenger RNA (modRNA) encoding the viral spike (S) glycoprotein of SARS-CoV-2
  • Lipids
    • (4-hydroxybutyl) azanediyl) bis (hexane-6,1-diyl) bis (ALC-3015)
    • (2- hexyldecanoate), 2-[(polyethylene glycol)-2000]-N, N-ditetradecylacetamide (ALC-0159)
    • 1,2-distearoyl-snglycero-3-phosphocholine (DPSC)
    • cholesterol
  • Salts
    • potassium chloride
    • potassium phosphate monobasic
    • sodium chloride
    • basic sodium phosphate dihydrate
  • Other

Reading the ingredient list is like looking at the side of a cereal box, except you need a degree in organic chemistry to figure it out. We enlisted the help of various scientists and biotech entrepreneurs to figure out what each of the ingredients does and make educated guesses about others.


Pfizer’s vaccine is the first on the market that consists of actual genetic information from a virus in the form of messenger RNA, or mRNA, a type of molecule whose usual job is to carry copies of genetic instructions around. ‘a cell to guide the assembly of proteins. . Imagine an mRNA as a long magnetic strip with instructions on it. This is a pretty delicate thing, and this is why Pfizer’s vaccine should be stored at -100 degrees Fahrenheit.

The new vaccine, administered by injection into the muscle of the arm, contains an RNA sequence taken from the virus itself; it causes cells to make the large “peak” protein of the coronavirus, which the pathogen uses to freeze on and enter a person’s cells. On its own, without the rest of the virus, the peak is fairly harmless. But your body always reacts to it, mounting a reaction. This is what leaves you immune and ready to fend off the real virus if it presents itself.

The vaccine’s mRNA, of course, is not quite the same as your body’s. This is good, because a cell is full of defenses ready to cut RNA, especially those that do not belong to it. To avoid this, so-called “modified nucleosides” have been replaced by some of the building blocks of mRNA.

But Pfizer is holding back a bit. The spike gene sequence can be altered in small ways for better performance, by means that include the exchange of letters. We don’t think Pfizer said exactly which sequence it uses, or which modified nucleosides. This means that the content of the plan may not be 100% public.


Pfizer’s vaccine, like Moderna’s, uses lipid nanoparticles to encapsulate RNA. Nanoparticles are basically tiny fatty spheres that protect mRNA and help it slide inside cells.

These particles are probably around 100 nanometers in diameter. Oddly enough, it’s roughly the same size as the coronavirus itself.

Pfizer says it uses four different lipids in a “defined ratio.” ALC-0315 lipid is the main ingredient in the formulation. That’s because it’s ionizable – it can be positively charged, and since RNA has a negative charge, they stick together. It is also a component that can cause side effects or allergic reactions. The other lipids, one of which is the familiar cholesterol molecule, are “helpers” that give nanoparticles structural integrity or prevent them from clumping together. During manufacturing, RNA and lipids are stirred in a bubbling mixture to form what the FDA describes as a “white to off-white” frozen liquid.


The Pfizer vaccine contains four salts, one of which is regular table salt. Together, these salts are better known as phosphate buffered saline, or PBS, a very common ingredient that keeps the pH, or acidity, of the vaccine close to that of a person’s body. You will understand how important it is if you have ever squeezed lemon juice out of a cut. Substances with poor acidity can damage cells or degrade quickly.


The vaccine contains regular old sugar, also called sucrose. It acts here as a cryoprotectant to protect the nanoparticles when they are frozen and prevent them from sticking together. Pfizer vaccine should be frozen at approximately -100 ° F until used.

Saline solution

Before injection, the vaccine is mixed with water containing sodium chloride or common salt, just like many drugs that are given intravenously. Again, the idea is that the injection should more or less match the salt content of the blood.

No preservative

Pfizer is keen to say that its blend of lipid nanoparticles and mRNA is “preservative-free”. Indeed, a preservative used in other vaccines, thimerosal (which contains mercury and is there to kill any bacteria that could contaminate a vial), has been at the center of concerns about whether vaccines cause autism. . US Centers for Disease Control Says Thimerosal Safe; despite this, its use is being phased out. There is no thimerosal – or any other preservative – in Pfizer vaccine. No microchips either.

The vaccine is still known by the code name BTN162, but once it is cleared, expect Pfizer to give it a new trade name that conveys something about what it contains and what it promises. for the world.

We thank the following people for explaining the ingredients of the vaccine: Jacob Becraft and Aalok Shah, Strand Therapeutics; Yizhou Dong, Ohio State University; Jason Underwood, Pacific Biosciences; Andrey Zarur, Greenlight Biosciences; Charles L. Cooney, MIT; and the communications teams of Pfizer and Moderna Therapeutics.




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