These are the ingredients in a COVID-19 vaccine

Around the world, there is a concerted effort under way to vaccinate as many people as possible against COVID-19, as quickly as possible. After slow starts in some countries, steady progress is now being made - although the rollout remains unequal.

The complex nature of the vaccine manufacturing and supply chain was described in a British Medical Journal blog by Charles Clift, a senior consulting Fellow at the Centre for Universal Health at Chatham House in London.

“Current annual production of all vaccines in the world is about 5 billion doses,” Clift said. “Yet this year the aim is to produce as much COVID-19 vaccine as possible to meet projected demand … estimated (at) about 9.5 billion doses, which has never been done before."

One of the shortages facing the vaccines sector includes the availability of skilled personnel, Clift explained. The composition of the vaccines themselves are another part of the challenge. Clift said that some COVID-19 vaccines require 280 separate inputs: “These range from the biological materials to grow the vaccine through a wide range of technical kit necessary for production to the vials that contain the finished product.”

The World Health Organization (WHO) has been heavily involved in disseminating clear, accessible information about the virus since early 2020. It’s no surprise, then, that WHO is doing something similar to help people understand the process of making the vaccines, too – including what some of those 280 inputs involve.

Here is the list of what goes into a COVID-19 vaccine, according to the WHO’s information. Note that the details here are generic and apply to all vaccines, this is not a breakdown of the specific compounds each of the COVID-19 vaccines contains.

1. Antigen

This is the active component that all vaccines contain. Created to resemble or mimic a particular disease or infection, or pathogen, the antigen’s purpose is to provoke your immune system. By doing that, it is laying the groundwork for future immune responses to an actual infection by the pathogen, in this case the COVID-19 virus.

2. Preservatives

If a vaccine comes as a single dose, it may not contain any preservatives. But some are delivered in larger vials, designed for multiple shots, in which case they need something to prevent the vaccine spoiling once exposed to the air. One of the most commonly used preservatives is 2-phenoxyethanol, which is also used as a perfume fixative, insect repellent and an antiseptic.

3. Stabilizers

Sugars (lactose, sucrose), amino acids (glycine), gelatin, and proteins are all used as stabilizers in vaccines. They are there to prevent chemical reactions taking place within the vaccine. One of the often-used proteins is recombinant human albumin. This is made from yeast and although it resembles human serum, it contains no human or other animal material.

4. Surfactants

While stabilizers stop vaccine components mixing and reacting, surfactants are there to keep all the ingredients mixed together. Without surfactants, there could be separation of ingredients, leading to sediment or clumps forming.

5. Residuals

Different manufacturing processes use different non-active ingredients. Trace elements of these non-active elements are present in the final vaccine and are known as residuals. They may be things like yeast or egg protein, or even antibiotics. They are in such tiny amounts that they are measured in parts-per-billion.

6. Diluent

The greatest ingredient, by volume, in a vaccine is the diluent. As the name suggests, it is the liquid used to dilute the vaccine to achieve the right concentration. Usually, the vaccine diluent is sterile water.

7. Adjuvant

Some vaccines contain small amounts of aluminium salts to help trigger a stronger immune response. These adjuvants work by stimulating immune cells near the injection site. Aluminium is sometimes the subject of alarmist concerns, but people routinely come into contact with aluminium through food and drink and it has been shown not to cause long-term health problems, the WHO says.