FACT SHEET FOR RECIPIENTS AND CAREGIVERS
EMERGENCY USE AUTHORIZATION (EUA) OF
THE PFIZER-BIONTECH COVID-19 VACCINE TO PREVENT CORONAVIRUS DISEASE 2019 (COVID-19)
IN INDIVIDUALS 16 YEARS OF AGE AND OLDER
You are being offered the Pfizer-BioNTech COVID-19 Vaccine to prevent Coronavirus Disease 2019 (COVID-19) caused by SARS-CoV-2. This Fact Sheet contains information to help you understand the risks and benefits of the Pfizer-BioNTech COVID-19 Vaccine, which you may receive because there is currently a pandemic of COVID-19.
The Pfizer-BioNTech COVID-19 Vaccine is a vaccine and may prevent you from getting COVID-19. There is no U.S. Food and Drug Administration (FDA) approved vaccine to prevent COVID-19.
Read this Fact Sheet for information about the Pfizer-BioNTech COVID-19 Vaccine. Talk to the vaccination provider if you have questions. It is your choice to receive the Pfizer-BioNTech COVID-19 Vaccine.
The Pfizer-BioNTech COVID-19 Vaccine is administered as a 2-dose series, 3 weeks apart, into the muscle.
The Pfizer-BioNTech COVID-19 Vaccine may not protect everyone.
This Fact Sheet may have been updated. For the most recent Fact Sheet, please see
www.cvdvaccine.com.
WHAT YOU NEED TO KNOW BEFORE YOU GET THIS VACCINE
WHAT IS COVID-19?
COVID-19 disease is caused by a coronavirus called SARS-CoV-2. This type of coronavirus has not been seen before. You can get COVID-19 through contact with another person who has the virus. It is predominantly a respiratory illness that can affect other organs. People with COVID-19 have had a wide range of symptoms reported, ranging from mild symptoms to severe illness. Symptoms may appear 2 to 14 days after exposure to the virus. Symptoms may include: fever or chills; cough; shortness of breath; fatigue; muscle or body aches; headache; new loss of taste or smell; sore throat; congestion or runny nose; nausea or vomiting; diarrhea.
WHAT IS THE PFIZER-BIONTECH COVID-19 VACCINE?
The Pfizer-BioNTech COVID-19 Vaccine is an unapproved vaccine that may prevent COVID-19. There is no FDA-approved vaccine to prevent COVID-19.
The mRNA
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 transport copies of genetic instructions around a cell to guide the assembly of proteins. Imagine an mRNA as a long ticker tape carrying instructions. It's fairly delicate stuff, and that's why Pfizer's vaccine needs to be kept at around -100 °F (-73 °C) until it's used.
The new vaccine, delivered as a shot in the arm muscle, contains an RNA sequence taken from the virus itself; it causes cells to manufacture the big “spike” protein of the coronavirus, which the pathogen uses to glom onto a person’s cells and gain entry. On its own, without the rest of the virus, the spike is pretty harmless. But your body still reacts to it. This is what leaves you immunized and ready to repel the real virus if it turns up.
The mRNA in the vaccine, to be sure, isn’t quite the same as the stuff in your body. That’s good, because a cell is full of defenses ready to chop up RNA, especially any that doesn’t belong there. To avoid that, what’s known as “modified nucleosides” have been substituted for some of the mRNA building blocks.
But Pfizer is holding back a little. The spike gene sequence can be tweaked in small ways for better performance, by means that include swapping letters. We don’t think Pfizer has said exactly what sequence it is using, or what modified nucleosides. That means the content of the shot may not be 100% public.
The lipids
The Pfizer vaccine, like one from Moderna, uses lipid nanoparticles to encase the RNA. The nanoparticles are, basically, tiny greasy spheres that protect the mRNA and help it slide inside cells.
These particles are probably around 100 nanometers across. Curiously, that’s about the same size as the coronavirus itself.
Pfizer says it uses four different lipids in a “defined ratio.” The lipid ALC-0315 is the primary ingredient in the formulation. That’s because it’s ionizable—it can be given a positive charge, and since the RNA has a negative one, they stick together. It's also a component that can cause side-effects or allergic reactions. The other lipids, one of which is the familiar molecule cholesterol, are “helpers” that give structural integrity to the nanoparticles or stop them from clumping. During manufacturing, the RNA and the lipids are stirred into a bubbly mix to form what the FDA describes as a “white to off-white” frozen liquid.
Salts
The Pfizer vaccine contains four salts, one of which is ordinary 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’ll understand how important that is if you’ve ever squeezed lemon juice on a cut. Substances with the wrong acidity can injure cells or get quickly degraded.
Sugar
The vaccine includes plain old sugar, also called sucrose. It’s acting here as a cryoprotectant to safeguard the nanoparticles when they’re frozen and stop them from sticking together.
Saline solution
Before injection, the vaccine is mixed with water containing sodium chloride, or ordinary salt, just as many intravenously delivered drugs are. Again, the idea is that the injection should more or less match the salt content of the blood.
No preservatives
Pfizer makes a point of saying its mixture of lipid nanoparticles and mRNA is “preservative-free.” That’s because a preservative that’s been used in other vaccines, thimerosal (which contains mercury and is there to kill any bacteria that might contaminate a vial), has been at the center of worries around over whether vaccines cause autism. The US Centers for Disease Control says thimerosal is safe; despite that, its use is being phased out. There is no thimerosal—or any other preservative—in the Pfizer vaccine. No microchips, either.
The vaccine is still known by the code name BNT162b, but once it’s authorized, expect Pfizer to give it a new, commercial name that conveys something about what’s in it and what it promises for the world.
We thank the following people for explaining the vaccine ingredients: 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 staffs of Pfizer and Moderna Therapeutics.
1 Revised: 25 February 2021
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