THE COVID VACCINATION COOKBOOK

How do you make an effective vaccine? Simply follow one of these recipes. Check your pantry: the ingredients aren’t nearly as exotic as some sceptics might suspect. ELLEN PHIDDIAN reports.

If you don’t want vaccines inside your body, it might be time to take a closer look at what you’re eating – and also learn more about cholesterol and salt. ELLEN PHIDDIAN analyses what’s actually in the doses, and discovers the ingredients are more familiar than you expect.

It began, as many things do, with a need, a curiosity, and an intriguing story. In the 18th century, smallpox was a global scourge. About a third of those who caught the disease died; survivors were left scarred, sometimes disfigured. From uncertain origins, smallpox had spread across the world through human movement – for trade, conquest and exploration. Early control methods such as variolation – scratching pus from smallpox sores into the skin of a disease-free person (named after the virus, Variola) – were only mildly successful.

In 1796, English physician Edward Jenner noted the accepted wisdom that milkmaids who’d caught cowpox – a similar but harmless cousin of smallpox – were more protected from the deadlier virus. Jenner guessed that cowpox might offer protection and, to test his theory, took pus from a cowpox sore on the hand of milkmaid Sarah Nelmes, who’d caught the infection from a milker named Blossom. Then, he injected it into both arms of James Phipps, the nineyear-old son of his gardener. Months later, Jenner directly exposed Phipps several times to variola virus, but Phipps never developed smallpox. After successfully testing his methodology on 23 more people, Jenner published On the Origin of the Vaccine Inoculation in 1801.

Jenner is considered the father of vaccination (he invented the term Variolae vaccinae: smallpox of the cow) – but in truth he built on existing knowledge. Chinese and Indian physicians had pioneered variolation (simple idea: people don’t tend to get sick with the same disease twice), and Lady Mary Montagu imported the idea from Constantinople to England in the 1720s.

Nonetheless, Jenner’s ethically dubious tests provided a critical discovery: that it was possible to give someone immunity to a disease without giving them the actual disease.

The smallpox vaccine is now known as “attenuated”: a live pathogen that is similar to the wild type, but less dangerous (as long as you don’t have a compromised immune system). During the early decades of the 19th century, attenuated vaccines were created to prevent a range of pathogens, both bacterial (such as tuberculosis) and viral (yellow fever).

By the late 19th century, scientists in both the US and France found that if bacteria was killed gently by careful heating, or using certain chemical treatments, it could still provoke an immune response. The “inactivated” vaccine was born, and was used to prevent typhoid and cholera, among other bacterial diseases. It took a few more decades to figure out how to inactivate a virus – they’re a lot smaller than bacteria, and trickier to “kill” – but inactivated influenza vaccines were available by the 1930s.

In 1923, UK researchers Alexander Glenny and Barbara Hopkins made another leap by creating a diphtheria vaccine that contained purified and treated bacteria toxins. Recipients developed immunity to the toxins without ever being exposed to the bacteria itself.

But vaccine invention has remained highly specific to the target disease: a trick for making a measles vaccine is unlikely to help the invention of a protective treatment for meningococcal, for example.

Understanding DNA – and the way it triggers RNA and then protein production – was the next big leap. What if you could just add the DNA for part of a virus to our bodies, and let our cells do all the hard work?

In 2014, spurred by the Ebola outbreak in West Africa, a “viral vector” vaccine began Phase 1 trials. This used a harmless, non-ebola virus to get a section of Ebola DNA into the nucleus of human cells. Those cells then transcribe the DNA into RNA, which in turn makes Ebola proteins (but not the whole virus), for our immune system to learn how to destroy.

It was the first widespread success for the viral vector. It was officially approved by the WHO in November 2019: safety standards had increased since Jenner’s day, and five years from conception to rollout was remarkably fast.

But researchers were already considering another way to simplify vaccines: would it be possible to skip the vector and DNA steps, and put the messenger RNA (or MRNA) directly into our bodies? (See our story on page 40 for that process.)

Several biotechnology companies – including Pfizer and Moderna – spent the 2010s figuring out the best jacket for the MRNA, and when COVID-19 broke out in late 2019, MRNA vaccine makers were ready. Here we unpack exactly what’s in three current vaccines: what they are, why they’re there, and why all those chemical compounds probably aren’t as scary as they sound…

INGREDIENTS Active Ingredient: BNT162B2 [MRNA] Lipid Nanoparticle Coatings:

a

ALC-0315: ((4-hydroxybutyl)azanediyl)

bis(hexane-6,1-diyl)bis(2-hexyldecanoate) ALC-0159: 2-[(polyethylene glycol)-2000]n,n-ditetradecylacetamide

DSPC: distearoylphosphatidylcholine cholesterol

Buffers:

b monobasic potassium phosphate

c dibasic sodium phosphate dihydrate

d potassium chloride

e sodium chloride

f Stabilising sugar: sucrose

g Solvent: water

ACTIVE INGREDIENT

This is the now-famous MRNA, or messenger RNA, which the body uses to make coronavirus spike proteins, triggering an immune response that should protect you against the real coronavirus. Interestingly, Pfizer’s MRNA is slightly different to naturally occurring MRNA – it’s been nucleoside-modified, which means one of the “coding” bases, uracil, has been swapped out for a molecule with a similar, but not identical, shape. This is a trick discovered more than 15 years ago – it stops the immune system from recognising and destroying the foreign MRNA before it can be used to make spike proteins.

LIPID NANOPARTICLE COATINGS

In order to make spike proteins, the MRNA has to get inside our cells, and our cells have oily membranes that repel molecules like MRNA. This is why the vaccine has four different lipids (long, fatty molecules that are more similar to cell membranes) coating the MRNA. They form nanometre-sized blobs and are hence known as “lipid nanoparticles”.

Pfizer’s combination of lipids has been developed by a Canadian company called Acuitas, which has been researching different combinations of lipids for therapeutics for the past decade.

This combination of four different lipids has been judged by Pfizer and Acuitas to be most effective at getting the MRNA into cells. Three of the lipids (ALC0315, ALC-0159 and DSPC) are synthetically designed and have previously been used in therapeutic treatments, while the fourth (cholesterol) is a molecule of which our bodies already contain several grams.

BUFFERS

The MRNA in the vaccine – and indeed, the molecules in our bodies – are remarkably sensitive to acidity, or ph. Salts are added because they can act as ph buffers, preventing a solution from becoming too acidic or basic. The four salts in the Pfizer vaccine are designed to keep the ph consistent over time. Two of the salts (monobasic potassium phosphate and dibasic sodium phosphate dihydrate) are also used in some pharmaceutical treatments (such as treating low blood phosphate levels), as well as fertilisers and food additives (as a buffering agent, or to stabilise and control acidity and moisture), while potassium chloride and sodium chloride (table salt) are common, naturally occurring substances used as flavour enhancers and preservatives in many food products.

STABILISING SUGAR

Sucrose (sugar, identical to commercial white sugar) has been added to the vaccine to keep other ingredients stable, particularly as it’s stored at low temperatures (TGA requires longer-term storage at -90°C to -60°C; unopened vials can be stored and transported at -25°C to -15°C for up to two weeks).

SOLVENT

Finally, these ingredients need to occur in liquid form, so a vaccine requires something to dissolve and mix them. Fortunately, water is the perfect molecule to do this, which is why it’s the final addition to the vaccine.

Vaccine ingredient lists may look scary, but many of their substances are found in common foods. We’ve linked the chemicals to an example of what they’re in.

INGREDIENTS Active Ingredient:

5 x 1010 CHADOX1-S (recombinant) viral particles

Buffers:

a L-histidine

L-histidine hydrochloride monohydrate

b magnesium chloride hexahydrate

c sodium chloride

d Emulsifier: polysorbate 80

Preservatives:

e ethanol

disodium edetate dihydrate

Other ingredients:

f sucrose

g water

ACTIVE INGREDIENT

The “viral vector” at the heart of the Oxford-astrazeneca vaccine is a tame virus – an adenovirus (which often presents as conjunctivitis or tonsillitis), not a coronavirus – that contains DNA to make SARS-COV-2 spike proteins, which will trigger your immune system.

The adenovirus has been modified so that it can’t replicate or harm people. It’s modelled on an adenovirus originally found in a chimpanzee, although no chimps were used in the vaccine’s production. Instead, it’s grown in lab-based cells, which come from modified cells originally taken from a human kidney. In Australia, the viral growing is done in Melbourne. Because Astrazeneca’s active ingredient comes with its own coating package in the form of an adenovirus, it doesn’t need lipids like the Pfizer vaccine. It does, however, need molecules to buffer the ph and keep it stable – as well as a couple of preservatives.

BUFFERS

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 consistent.

Both salts are naturally occurring minerals, while L-histidine is a molecule known as an amino acid. These compounds are what our proteins are made of, so there’s already plenty of L-histidine inside you. L-histidine hydrochloride monohydrate is similar to histidine (hence the name), and it’s also been used in foods, cosmetics and soaps.

EMULSIFIER

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

Polysorbate 80 is a common food additive (for example in ice cream and gelatin), because of its emulsifying properties; it’s also been used in other, NON-COVID, vaccines.

PRESERVATIVES

While it’s made and kept in sterile conditions, Astrazeneca’s vaccine still uses preservatives to prevent any sort of contamination from the vials or manufacturing process. (Pfizer has opted to avoid preservatives, which means the vaccine requires fewer ingredients, but some doses have been discarded because they can’t be guaranteed non-contaminated.)

As well as being a preservative, disodium edetate dihydrate (EDTA) is an approved medication for treating some types of metal poisoning, such as lead poisoning.

The ethanol is identical to the alcohol you get in hand sanitiser, beer and wine and spirits – but at a concentration of less than 0.005% in a 0.5-millimetre dose, it’s not going to affect your blood alcohol content.

OTHER INGREDIENTS

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