By: Rachel Ford
This article will break down the ingredients, chemical processes and functions of the Pfizer and Moderna mRNA vaccines, and provide some more information about the side effects, differences between vaccines, and when the general population can expect to get them. Though I will try to remain purely scientific, any political views implied/expressed are my own and not representative of Shorecrest, the Chronicle, or all AP Biology students. Author credentials: I am in AP Biology and spend a lot of time looking things up on the Internet.
Disclaimer: this will not necessarily be a fun read but you will feel like an intellectual and also Biology is your life™.
Moderna Ingredient Breakdown
mRNA: messenger RNA, codes to produce proteins
Lipids: the building blocks of fats, used to safely transport the RNA into the cell
- SM-102: unique to the vaccine, a lipid synthesized by Moderna that breaks into nanoparticles to better encapsulate the RNA
- 1,2-dimyristoyl-rac-glycero3-methoxypolyethylene: also used to form lipid nanoparticles
- glycol-2000 [PEG2000-DMG]: same as above
- 1,2-distearoyl-snglycero-3-phosphocholine [DSPC]: phospholipid used to create liposomes, membrane rings or vesicles that deliver items in the cell
- Cholesterol: a type of lipid that is abundant in the body
- Tromethamine, Tromethamine hydrochloride: a type of salt used to balance electrolytes, found in treatments for kidney diseases, probably used to regulate pH
- Acetic acid: found in vinegar, probably used to regulate the vaccines’ pH
- Sodium acetate: a common stabilizer, found in IV fluids
- Sucrose: sugar
Pfizer Ingredient Breakdown
- 2 [(polyethylene glycol)-2000]-N,N-ditetradecylacetamide
- 1,2-Distearoyl-sn-glycero-3- phosphocholine
- All used for the same purposes as the other lipids just slightly different formulas
- Potassium chloride: A salt that is essential to the human body and also found in fertilizers
- Monobasic potassium phosphate: A salt also in the body used to regulate calcium in urine and prevent kidney stones
- Sodium chloride: table salt
- Dibasic sodium phosphate dihydrate: Another salt, found in food mixes for anti-caking and to regulate pH
Key differences between the two
- Moderna: 2 doses, 100 μg each, administered 1 month apart
- Pfizer: 2 doses, 0.3ml each, administered 3 weeks apart
- Moderna: recommended for ages 18 and up
- Pfizer: recommended for ages 16 and up
- Moderna: kept at -20C, -4F, can be stored at refrigerator temperature for 30 days
- Pfizer: kept at -70C, -94F
How does an mRNA vaccine work in general?
The first, key fact to keep in mind is that unlike other vaccines, these 2 mRNA COVID-19 vaccines do not contain any amount of the actual virus. Both vaccines use mRNA, shortened from “messenger RNA”, which is a piece of RNA that is read by ribosomes to produce a specific protein. RNA, or in full ribonucleic acid, is a copy of the cell’s DNA that codes for a gene and is produced naturally within the cell’s nucleus; ribosomes are found in all cells and are composed of RNA and proteins. The mRNA “enters” the ribosome (it actually is encapsulated between the ribosome’s two subunits), and is “read” by the ribosome, which arranges the correct sequence of amino acids brought by tRNA (transfer RNA) to produce the protein.
In the case of the Moderna and Pfizer vaccines, the mRNA codes to produce a protein known as a spike glycoprotein, the same protein on the exterior of the virus that creates its signature spiky shape and gives the virus its name—corona means crown in Latin. The protein itself is harmless, composed of a chain of saccharides (sugar) covalently bonded to amino acid chains, and is found in the body in the form of mucins which are located in the nose and throat mucosal membranes. When the ribosomes produce the protein (which happens in the cell, not the nucleus, therefore the vaccine cannot “alter your DNA!!”), the immune system recognizes it as foreign and produces antibodies to destroy the spike proteins. Producing these antibodies will “prime” the cell (actually the memory T-cells) to produce them again much faster and en masse when the protein reappears in the body on the coronavirus.
Why does it produce a specific protein?
The spike glycoprotein on the coronavirus binds to a receptor, the human angiotensin converting enzyme 2 (hACE2), to initiate infection. This enzyme is supposed to convert the hormone angiotensin I, which relaxes the blood vessels, to angiotensin II, which constricts them, in order to regulate blood pressure. The coronavirus uses this attachment to the receptor to enter cells and reproduce by “hijacking” the nucleus to produce more of the virus.
Verified post-vaccination side effects
Pfizer: injection site pain, tiredness, headache, muscle pain, chills, joint pain, fever, injection site swelling, injection site redness, nausea, swollen lymph nodes
Moderna: pain at injection site (reported by 91.6% of trial participants), fatigue (68.5%), headache (63.0%), muscle pain (59.6%), joint pain (44.8%), and chills (43.4%)
- A statistic that has made the news is that there were three reports of facial paralysis (Bell’s palsy) in the vaccine group. While the palsy is not life threatening and will resolve itself within 6 months, 3 cases out of 30,350 participants is a rate of 0.0099% compared to the overall population rate of 0.02% and was decided by Moderna and the FDA to be not statistically significant enough to warrant withdrawal.
When can we expect the vaccine to be distributed widely enough for herd immunity?
Herd immunity for COVID is estimated to be achievable when 50 to 67% of the population are resistant to the virus. According to Dr. Fauci in December, they expect to reach herd immunity by the fall.
When will young people be able to get it?
Here is the part of the article you’ll all be interested in (though the rest was riveting): when can we get the vaccine? According again to Fauci as of February 19th, he believes “healthy young people” will be able to get the vaccine in May or June.
Moderna Fact Sheet: Vaccines and Related Biological Products Advisory Committee December 17, 2020 Meeting Briefing Document
Pfizer Fact Sheet: Pfizer COVID-19 Vaccine EUA Fact Sheet for Recipients and Caregiver