Pfizer COVID-19 vaccine facts – scientific evidence to deal with misinformation

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Because the Pfizer COVID-19 vaccine is ready to launch in many countries, it is time that we provide the facts about the vaccine. This will be different than my myth debunking article (which will be constantly updated as the anti-vaxxers get going with their lies and disinformation), as this article will try to make sure that everyone is on the same page with what this vaccine is. 

Almost all of the information will come from the Pfizer/BioNTech COVID-19 mRNA vaccine documents that were submitted for review by the Vaccines and Related Biological Products Advisory Committee (VRBPAC) in advance of an emergency use authorization (EUA) that was issued by the FDA on the evening of 11 December 2020. I read through most of the material to save you all time during this holiday season (so please like this article and share it across the planet).

I’m going to just hit what I think will be the most important points about the vaccine’s safety, effectiveness, ingredients, and other related information. Because these Pfizer COVID-19 vaccine facts will be most useful in debunking wild claims that you might read on the internet. I am planning to do the same with the Moderna vaccine, so stay tuned once VRBPAC reviews their data and the FDA issues an EUA.

What are mRNA vaccines?

I’ve written this several times with regards to both the Pfizer and Modern mRNA vaccines, but it bears repeating, because a lot of people may come to this article for the first time. 

The Pfizer and Moderna Therapeutics COVID-19 vaccines are mRNA vaccines that rely upon an mRNA, or messenger RNA, molecule to induce an immune response. However, it does not do this directly.

Normally, during the process called transcription, RNA polymerase makes a copy of a gene from its DNA to mRNA as signaled by the cell. In other words, the mRNA sequences in the cell usually correspond directly to the DNA sequences in our genes. These mRNA sequences “carry” that genetic message to a ribosome for translation, where tRNA triplets, which code for one amino acid, attach to the appropriate mRNA triplet, adding one amino acid to the protein chain. 

As in DNA, genetic information in mRNA is contained in the sequence of nucleotides, which are arranged into codons consisting of three ribonucleotides each. Each codon codes for a specific amino acid, except the stop codons, which terminate protein synthesis.

AT this point, note that the mRNA does nothing to the DNA strand in your genes – it merely reads the sequence.

Yes, that’s a lot of cell biology, though I took years of courses in cell biology, so trust me when I say I barely touched the surface. If you want to take a deep dive into the science of mRNA and mRNA vaccines, my friend Edward Nirenberg wrote two articles that will satisfy your desires – they really make it clear how this all works and doesn’t work.

However, here’s a basic video that shows how this works.

Alan McHughen, in his outstanding book, “DNA Demystified: Unraveling the Double Helix,” describes how mRNA works:

When an mRNA strand exits the nucleus and enters the cytoplasm, it attaches to ribosomes, and this is where protein synthesis progresses. The ribosome reads the base sequence of the mRNA, three bases at a time. Each three-base triplet, called a codon, specifies a particular amino acid, except for a few with regulatory functions (e.g., UGA =“Stop!”).

If the first three-base codon is AUG, then a molecule of the amino acid methionine is brought into place. If the next triplet is AAA, that brings in the amino acid lysine. The methionine and lysine molecules are attached together. The next triplet is, say, GCC, and that brings in alanine, which is attached to the lysine. The ribosome has read nine bases, AUGAAAGCC, and compiled a short chain of three amino acids, abbreviated Met-Lys-Ala, or MKA (see amino acid abbreviations here).

The ribosome continues reading all of the mRNA bases until it hits a stop signal—which is also a triplet codon such as UGA—and the now long chain of amino acids falls loose. This chain may be a functional protein immediately, or, more usually, it might undergo some additional post-translational processing by enzymes to become active.

mrna vaccines

Once the mRNA has created a protein, it is then ripped apart by enzymes in the cell, so that the individual RNA nucleotides can go back to being reused in a whole new mRNA sequence. The cellular machinery of translating DNA into proteins is constantly recirculating itself.

The mRNA vaccine technology relies upon a specific mRNA sequence to kickstart the endogenous production of proteins that are structurally equivalent to the viral antigens. The mRNA sequences in the vaccine enter the cell (with a carrier protein), heads to the ribosomes to create the SARS-CoV-2 antigens. These antigens will depart the cell and will trigger the body’s adaptive immune system to produce antibodies effective against the actual target, in this case, the S-protein or spike on the SARS-CoV-2 virus.

One more thing – the antigens produced by these mRNA sequences are biologically inert. They will induce an immune response, but they will not cause any other biological effect including becoming pathogenic.

So, let’s summarize. The mRNA vaccines make use of the cell’s ribosome to create the S-protein of the SARS-CoV-2 virus. That antigen induces an adaptive immune system response that will “remember” that antigen allowing the immune system to quickly attack the virus if it shows up.

Someone used this analogy to describe how mRNA works. Let’s say you have a book that represents the genetic code (lots of people describe our genetic code as the official manual of our individual person). You then scan that book in a copy machine, and now you have a bunch of papers that are an image of the original book. The copy does not change the original book. It can’t.

Pfizer COVID-19 vaccine facts

I am going to review the facts about the Pfizer/BioNTech mRNA COVID-19 vaccine one-by-one. Most of this information will end up in a vaccine package insert, so knowing this information now will help to deal with the inevitable anti-vaccine disinformation campaign.

Basically, I will delve into the following key facts:

  1. Ingredients
  2. Dosage
  3. Clinical trial demographics and included comorbidities
  4. Adverse events
  5. Effectiveness
  6. Other information

So let’s start.


As any of us who have had to deal with anti-vaccine misinformation, attacking the ingredients is part of the standard operations. Here are the ingredients, and an explanation of what it is and why they are in the vaccine:

  • mRNA. These mRNA fragments cause the ribosomes of cells to produce the viral spike glycoprotein of SARS-CoV-2. As I described above, these will induce the adaptive immune system to “remember” the antigen. 
  • Lipids. Because the mRNA fragments would be broken down to constituent nucleotides if directly injected, they are surrounded by lipids that allow them to enter the cell. These lipids are – (4-hydroxybutyl)azanediyl)bis(hexane-6,1-diyl)bis(2-hexyldecanoate), 2-[(polyethylene glycol)-2000]-N,N-ditetradecylacetamide, 1,2-distearoyl-snglycero-3-phosphocholine, and cholesterol.  Yes, these sound like “chemicals,” let’s be clear that all lipids in all organisms are “chemicals.” As an example, here is the name for simple cholesterol circulating in your blood – (3S,8S,9S,10R,13R,14S,17R)-10,13-dimethyl-17-[(2R)-6-methylheptan-2-yl]-2,3,4,7,8,9,11,12,14,15,16,17-dodecahydro-1H-cyclopenta[a]phenanthren-3-ol. The lipids included in this vaccine have been constructed to “carry” the mRNA fragment from the injection site to the cell, attach to the cell, then move the mRNA into the cell. This is a typical endogenous cell membrane transport system that is native to all cells. 
  • Preservatives. None, period. So the first person who says there is thiomersal or something else in here can go take a time-out in the corner. 
  • Potassium chloride. A salt used to buffer the solution so that it doesn’t break down.
  • Monobasic potassium phosphate. A salt used to buffer the solution so that it doesn’t break down.
  • Sodium chloride. A salt used to buffer the solution so that it doesn’t break down.
  • Dibasic sodium phosphate dihydrate. A salt used to buffer the solution so that it doesn’t break down.
  • Sucrose. A disaccharide of glucose and fructose, otherwise known as table sugar. It is also used to buffer the solution.

Unless you have some sort of phobia towards long chemical names, none of these ingredients will cause any issue with any human at the incredibly low concentrations found in the vaccine. Sure, you will die if you consumed a 100 grams of potassium chloride, but this vaccine only includes 100 µg (1-millionth of a gram) of the salt. And no, a little isn’t going to hurt you, because that’s not how toxicology works – the dose makes the poison


The Pfizer-BioNTech COVID-19 Vaccine is supplied as a frozen, between-80°C to -60°C (-112°F to -76°F for those of you who refuse to use metric) in a multi-dose (5-dose) vial. The vaccine must be thawed and diluted in its original vial with 1.8 mL of sterile 0.9% Sodium Chloride Injection, USP prior to administration. Because the vial is multi-dose, it must all be used, it cannot be refrozen and must be used within 6 hours after dilution.

After dilution, the vial contains 5 doses of 0.3 mL per dose. The multiple-dose vials must be stored between 2°C to 25°C (35°F to 77°F) and used within 6 hours from the time of dilution.

The vaccine must be administered intramuscularly (IM) as a series of two 30 μg doses (0.3 mL each) 21 days apart.

Clinical trial demographics and included comorbidities

The clinical trial included 43,448 individuals roughly divided equally into placebo and vaccinated groups. The study was conducted in the USA, Argentina, Brazil, Germany, South Africa, and Turkey.

The most common comorbidities included in the study (both the placebo and vaccine groups) – obesity (35.1%), diabetes (7.8%), and chronic pulmonary disease (7.8%).

Adverse events

Most common reactions were assorted injection site reactions (84.1%), fatigue (63.9%), headache (55.1%), muscle pain (38.3%), joint pain (23.6%), fever (14.2%). These are considered minor events that are associated with either the injection or the general immune response (that is typical to almost all vaccines).

Pfizer COVID-19 vaccine facts

The incidence of serious adverse reactions was extremely low, less than 0.5%, but they occurred equally in both the vaccinated and placebo groups, meaning that it’s almost impossible to find a causal relationship between them and the vaccine. 

Just to be completely transparent, individuals did die during the study, because people die irrespective of vaccines. It is not logical to think that no one would die during a clinical trial.

There were six total deaths, two were in the vaccine group, and four in the placebo group. None of the deaths were linked to the vaccine.

Pfizer COVID-19 vaccine facts


The effectiveness facts of the Pfizer/BioNTech COVID-19 vaccine efficacy after two doses was 94.6%, which means that the vaccinated group had an approximately 95% lower risk of contracting COVID-19. The duration of the vaccine effectiveness is currently at 60 days, but the two groups will be monitored for up to 30 months, so the duration of the effectiveness may increase with more data.

In addition, vaccine effectiveness against severe COVID-19 disease was 66.4% after two doses and 88.9% after one dose. Please do not read too much into that data as they are based on extremely small numbers, and the confidence interval is extremely large. 

Other Information

Phase 3 clinical trials are not the endpoint for research on any vaccine, including vaccines. Pfizer is planning long-term monitoring of the vaccine, watching for any safety signals and changes in vaccine effectiveness over time. We will probably see many peer-reviewed published articles appearing every month with new data from this vaccine.


In case you do not want to read all the details above, here is a summary of the Pfizer COVID-19 vaccine facts:

  1. Ingredients – nothing remarkable
  2. Dosage – two doses separated by 21 days
  3. Clinical trial demographics and included comorbidities – 43,448 individuals roughly divided equally between placebo and vaccine groups. The study was performed in several countries, was balanced demographically, and included numerous comorbidities.
  4. Adverse events – minor adverse events were expected as with most vaccines. Serious adverse events and deaths were not vaccine-related, and the incidence was approximately equal in both vaccine and placebo groups.
  5. Effectiveness – the vaccine reduces the risk of COVID-19 by 94.6% compared to placebo.
  6. Pfizer will continue to monitor the safety and effectiveness of the vaccine over the next 30 months at least.


I generally refer to this vaccine as the Pfizer COVID-19 mRNA vaccine. This isn’t meant to ignore that the vaccine was actually developed by the German company, BioNTech. However, almost all of the heavy lifting of the clinical trials, FDA submissions, and manufacturing is being done by Pfizer. This happens all of the time with new drugs – one company invents it, but a larger, wealthier partner gets it to market. We owe a big debt to BioNTech, but it’s going to be a Pfizer vaccine from now to the end of this pandemic.

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The Original Skeptical Raptor
Chief Executive Officer at SkepticalRaptor
Lifetime lover of science, especially biomedical research. Spent years in academics, business development, research, and traveling the world shilling for Big Pharma. I love sports, mostly college basketball and football, hockey, and baseball. I enjoy great food and intelligent conversation. And a delicious morning coffee!