Coronavirus vaccine: How is a vaccine produced on a large scale?

The world over is ardently waiting for a vaccine to fight the COVID-19 pandemic. Over 140 medical groups and researchers are working on creating a COVID vaccine in perhaps, what is the shortest timeline ever.

Nonetheless, despite steady advancements and innovations, producing a vaccine which could inoculate billions against the disease is a mammoth task. Developing a vaccine is only one half of the struggle. Ramping up production, procuring ingredients in sizeable quantities is a big problem which requires a lot of funding as well. To ensure that the vaccine is readily acceptable and serves the purpose, there should be zero chances of errors happening. There are three main factors taken into consideration while mass-producing any vaccine. Here is a detailed explainer.

The way a vaccine works is that it trains our immune system to recognize and prevent virus and other pathogens. This is usually done by the introduction of antigens, which are the molecules present on all pathogens to trigger immunity.

Antigens are usually produced by growing virus-cell cultures in a lab-assisted facility and bioreactors. Viruses are allowed to develop and multiply in growth mediums which replicate human cells. Supportive nutrients like amino acids, carbohydrates and proteins are also introduced for the same. Once the virus completes its life-cycle, the growth medium is separated using special filters. What scientists then get is 'live attenuated viruses', which have been modified for use and are no longer harmful to humans and can be safely introduced in the system. This is the basis of a traditional vaccine model. Oxford University, Gameleya Institute and other companies making use of isolated strains are working in a similar manner.

The same way, some vaccines require the additional use of adjuvants, which can help increase immunity and offer stronger protection. They are often used in cases where a vaccine dose won't alone show the best results (for example, elderlies or those who are immuno-compromised).

Companies like GSK are working on making adjuvants available to be used with some vaccine candidates. Some of the most commonly used ingredients include the usage of preservatives like thimerosal, aluminium (which protect vaccines from contamination) and stabilizing additives like sugar, gelatin, which help preserve the active molecules in a vaccine from shifting forms and sustain during the production timelines. Formaldehyde is also often used to detoxify toxins and inactivate germs so as to ensure a person doesn't get sick. All of these might be used in fairly minute quantities but any form of disruption or non-availability could hamper the production of vaccines. Traditional vaccines also make use of scary (and limited) ingredients such as shark liver oil and horseshoe crab blood, which contain biological compounds helpful in testing a vaccine's efficacy.

Procuring ingredients or technology which would help avoid bacteria and other harmful germs from ruining its properties is essential and needed in large quantities. Some ingredients used are also put in place to ensure that the vaccine keeps on working in the body like it is supposed to.

Non-traditional vaccines are developed in a different way. Many new vaccines, like the ones being worked on right now, are made using DNA (ZyCOV-D) and mRNA technology (Moderna Inc., Pfizer-BionTech). These are novel scientific technologies which decode and copy figments of the virus's genetic material and once injected inside the body, program the cells to produce helpful antigens on its own. These kinds of vaccines are considered safer to use and make since there is a low risk of exposing a host to the virus and contracting infections. Such vaccines could also be best suited for those with existing medical allergies or sensitive to bioactive ingredients used in the making of a traditional vaccine. DNA and mRNA vaccines are also faster to make.

However, there do exist some possible weak points. mRNA technology has never been commercially used, for example, and Moderna's approach is the first of its kind. Secondly, these technologies degrade faster and special enzymes (such as vaccinia capping enzyme) have to be introduced for their maintenance. They are considered to be one of the most expensive ingredients in the world and hence, heavy funding is required to produce a vaccine in large volumes. Since they are still being researched on, the probability of developing side-effects, immune reactions post injection is a lot higher than traditional vaccines.

Another problem scientists are worried about is regarding the storage of vaccines. Since any vaccine which wins approvals would need to be supplied in millions, production facilities need to be designed in a way that vaccines are secure and safe. Similar problems could be encountered in the delivery process. Some vaccines, such as the ones made using mRNA technology need to be stored in extremely cold temperatures, which can't be made available in every region. To ensure they are effective, most vaccines must be kept between 2 and 8 degrees Celsius—from the time they are manufactured until they are administered similarly, some vaccines, such as DNA vaccines need to be administered in a different way as well. All these factors need to be checked before vaccines are administered to the masses.

Glass vial (which are usually the best medium to store a vaccine) manufacturers from India and across the world are also ramping up production to meet the need.