What’s in a COVID vaccine?

You may have heard a lot about how COVID vaccines work over the past year and how they are being rolled out. But scroll down a list of vaccine ingredients and you’ll see a long list of names that aren’t labeled in a helpful way with their purpose. Some may be familiar, but many will sound foreign and difficult to pronounce.

Vaccines are made up of an active ingredient (which elicits an immune response) and excipients (additional ingredients, which are there to help the active ingredient in some way). The excipients could stabilize the active ingredient, help it reach the right place in the body, prevent contamination, help with mixing or a combination of all of these.

Most of the excipients are food and pharmaceutical products approved for years, because it is much faster to test a new vaccine and get it approved if most of the components have already been used in humans.

Here are the ingredients of the three vaccines currently in play in the Australian rollout: Pfizer and AstraZeneca vaccines are both being delivered, while the Moderna vaccine is expected to arrive. late this year (awaiting TGA approval). As more vaccines are approved and ordered, we will update this list.

Pfizer-BioNTech

Ingredients:

• BNT162b2 [mRNA]
• ((4-hydroxybutyl) azanediyl) bis (hexane-6,1-diyl) bis (2-hexyldecanoate) (ALC-0315)
• 2-[(polyethylene glycol)-2000]-N, N-ditetradecylacetamide (ALC-0159)
• distearoylphosphatidylcholine (DSPC)
• cholesterol
• potassium chloride
• potassium phosphate monobasic
• sodium chloride
• dibasic sodium phosphate dihydrate
• sucrose
• water for injections

Active ingredient

• messenger ribonucleic acid – BNT162b2 [mRNA]

This is the famous MRNA, or messenger RNA, which the body uses to make advanced coronavirus proteins, triggering an immune response that should protect you against the real coronavirus. Interestingly, Pfizer’s mRNA is slightly different to natural mRNA – it has been modified by nucleosides, that is to say one of the bases of ‘coding’, uracil, has been replaced by a molecule of similar shape, but not identical. It’s a trick discovered over 15 years ago – it prevents the immune system from recognizing and destroying foreign mRNA before it can be used to make advanced proteins.

Lipid nanoparticle coatings

• ((4-hydroxybutyl) azanediyl) bis (hexane-6,1-diyl) bis (2-hexyldecanoate) (ALC-0315)
• 2-[(polyethylene glycol)-2000]-N, N-ditetradecylacetamide (ALC-0159)
• distearoylphosphatidylcholine (DSPC)
• cholesterol

In order to make advanced proteins, mRNA must obtain inside our cells, and our cells have oily membranes that repel molecules like mRNA. This is why the vaccine has four lipids (long, fatty molecules that look more like cell membranes) covering the mRNA. They form spots of nanometric size and are therefore called “lipid nanoparticles”.

Pfizer’s lipid combination was developed by a company called Acuitas, who has researched different combinations of lipids for therapeutic purposes over the past decade.

This combination of four different lipids has been found by Pfizer and Acuitas to be the most efficient at delivering mRNA into cells. Three of the lipids (ALC-0315, ALC-0159 and DSPC) are synthetic in design and had already been used in some therapeutic treatments, while the fourth (cholesterol) is a molecule of which our body already contains several grams.

Buffers

• potassium chloride
• potassium phosphate monobasic
• sodium chloride
• dibasic sodium phosphate dihydrate

The mRNA in the vaccine – and indeed, the molecules in our bodies – are remarkably sensitive to acidity, or pH. Salts are added as they can act as pH tampons, preventing a solution from becoming too acidic or basic. The four salts of the Pfizer vaccine are designed to keep the pH constant over time. Two of the salts (potassium phosphate monobasic and sodium phosphate dibasic dihydrate) are also used in some pharmaceutical treatments, as well as fertilizers and food additives, while potassium chloride and sodium chloride (table salt) are common natural substances.

Stabilizing sugar

Sucrose (sugar, identical to commercial white sugar) has been added to the vaccine to maintain the stability of the other ingredients, especially since it is stored at low temperatures.

A solvent

Finally, these ingredients must all be in liquid form, so a vaccine needs something to dissolve and mix them. Fortunately, water is the perfect molecule for doing this, which is why it is the latest addition to the vaccine.

Oxford-AstraZeneca

Ingredients:

• 5 x 1010 ChAdOx1-S viral particles (recombinant)
• L-histidine
• L-histidine hydrochloride monohydrate
• magnesium chloride hexahydrate
• polysorbate 80
• ethanol
• sucrose
• sodium chloride
• disodium edetate dihydrate
• water for injection

Active ingredient

• 5 x 1010 ChAdOx1-S viral particles (recombinant)

It is the “viral vector” that makes the Oxford-AstraZeneca vaccine a “viral vector” vaccine. It is a tame virus (a adenovirus, not a coronavirus) which contains advanced SARS-CoV-2 proteins, which will trigger your immune system.

The adenovirus has been modified so that it cannot replicate itself or harm people. It is modeled on an adenovirus originally found in a chimpanzee, although no chimpanzee has been involved in the production of this vaccine. Instead, it’s grown in lab cells, which have been cultured from cells that originally came from a human kidney and then genetically engineered. In Australia, viral growth is made in Melbourne.

Since the active ingredient in AstraZeneca comes with its own packaging as an adenovirus, it does not need lipids like the Pfizer vaccine. However, it does need molecules to buffer the pH and keep it stable, as well as some preservatives.

Buffers

• L-histidine
• L-histidine hydrochloride monohydrate
• magnesium chloride hexahydrate
• sodium chloride

Like the Pfizer vaccine, salts (magnesium chloride hexahydrate and sodium chloride) and amines (L-histidine and L-histidine hydrochloride monohydrate) are added to keep the pH constant.

Both salts are naturally occurring minerals, while L-histidine is a molecule known as amino acid. These compounds are the makeup of our proteins, so there is already a lot of L-histidine inside you. L-Histidine hydrochloride monohydrate is similar to histidine (hence its name), and it is also Already used in food, cosmetics and soaps.

Emulsifier

Oily things (like the exterior of adenoviruses) and watery things don’t mix well, so the AstraZeneca vaccine requires an emulsifier to combine them. An emulsifier is a molecule that has both hydrophobic (oily) and hydrophilic (aqueous) sections, allowing them to mix – detergents and know are a common example; lecithin in egg yolks is another.

Polysorbate 80 is a common food additive due to its emulsifying properties, and it has also been used in other non-COVID vaccines.

Preservatives

• ethanol
• disodium edetate dihydrate

Although stored under very sterile conditions, the AstraZeneca vaccine still uses preservatives to prevent any kind of contamination of the vials or the manufacturing process. (Pfizer chose to avoid preservatives, which means the vaccine requires fewer ingredients, but some doses have been discarded as they cannot be guaranteed uncontaminated.)

In addition to being a preservative, disodium edetate dihydrate (EDTA) is a approved drug to treat certain types of metal poisoning.

Ethanol is the same as the alcohol you get in hand sanitizer, beer, and wine, but at a concentration of less than 0.005% in a 0.5 millimeter dose, it will not affect your level of alcohol. blood alcohol level.

Other ingredients

As with the Pfizer vaccine, sugar is used to stabilize the ingredients and water is used to combine all the ingredients.

Modern

Ingredients:

• messenger ribonucleic acid (mRNA)
• SM-102
• polyethylene glycol [PEG] 2000 dimyristoylglycerol [DMG]
• cholesterol
• distearoylphosphatidylcholine (DSPC)
• tromethamine
• tromethamine hydrochloride
• acetic acid
• sodium acetate trihydrate
• sucrose
• the water

Active ingredient

• messenger ribonucleic acid (mRNA)

As with the Pfizer vaccine, the Moderna vaccine primers the immune system with MRNA. Moderna’s mRNA is also slightly different from natural mRNA (modified by nucleosides), so it doesn’t trigger the immune system in the wrong place.

Lipid nanoparticle coatings

• SM-102
• polyethylene glycol [PEG] 2000 dimyristoylglycerol [DMG]
• distearoylphosphatidylcholine (DSPC)
• cholesterol

Like the Pfizer vaccine, the Moderna vaccine mRNA needs an oily coating to allow it to enter cells, and again, lipids are key.

Two of the lipids used – DPSC and cholesterol – are identical to those in Pfizer’s vaccine. (In Moderna’s literature, DSPC is referred to as 1,2-distearoyl-sn-glycero-3-phosphocholine rather than distearoylphosphatidylcholine, but it’s the same molecule, with a different name, just as unpronounceable.)

The other two lipids are synthetically engineered. While the combination of lipid nanoparticles has been in development and testing for years, Moderna is currently in a phase legal battle with a smaller company, Arbutus, on patents on the specific combination of lipids – Moderna lost a patent, but it’s uncertain whether this entitles Arbutus to royalties on the profits made by Moderna on the vaccine (or other products). The merit of their development is therefore not clear, but at least two companies have devoted a lot of time and money.

Buffers

• tromethamine
• tromethamine hydrochloride
• acetic acid
• sodium acetate trihydrate

As with other vaccines, buffers are used to maintain the pH.

Tromethamine and tromethamine hydrochloride are very common buffers in chemical research, while you are probably more familiar with acetic acid as a component of vinegar. Another very common food additive is sodium acetate trihydrate (very similar to acetic acid).

Other ingredients

As with other vaccines, sugar and water are added to stabilize and mix the components.