Tracking The Covid-19 Vaccine: How It Will Kill The Coronavirus

The hunt for a Covid-19 vaccine is nearing its end (Photo: Gerd Altmann/ Pixabay)

THE DOC’S LAB by Dr. S A Siraj

Kolkata: Looks like we are finally entering the business end of things in our almighty pursuit of a Covid-19 vaccine.

Moncef Slaoui, who is the chief of the US government’s coronavirus vaccine effort, has announced the country’s plans to start vaccinating the masses from as early as December 11 – that’s just more than two weeks from now.

Of course, the ambitious plan relies entirely on a stable vaccine first getting market-ready by then and also subject to official clearance from the country’s Food and Drug Administration (FDA).

The development isn’t necessarily good news only for those on American soil.

It’s an indication that the global vaccine hunt is closing in on finally cracking the case. True that America will use all its muscle power to corner for itself much of the vaccine shots that will available. But the rest of the world will also hopefully get its due share, albeit in slightly delayed and staggered phases.   

There’s good news from many of the labs worldwide that are working to create a stable Covid-19 vaccine. Some of the labs have already stood out with their work. A few of them are closing in on the finish line.


Some of the front runners have tasted success in the Phase 3 trials of their experimental vaccines. And success at the mass-scale trials is a major, major step towards a breakthrough.

It’s important to understand how a vaccine is trialled – right from a quiet gingery start to a robust mass testing.

The trial phase is the most crucial period of a prospective vaccine. It’s like an acid test in which the creator of a vaccine gets to know whether it will practically work or not. Unforeseen loopholes can show up, like it has happened in one or two cases of the Covid-19 candidate vaccine trials. And the vaccine maker has to rush back to the drawing board to fix the issues.

How an experimental vaccine is tested or trialled is a very intriguing process. The first step is the pre-clinical testing, in which the vaccine is given to animals to see if it induces immune response.

Then comes Phase 1 of clinical testing, the first test involving humans. The vaccine is given to a small group of humans to see if it is safe and to observe the immune response it induces in the volunteers.

Next is the Phase 2 trial. It’s a much wider experiment in which the vaccine is given to hundreds of people. Experts closely look for how safe the vaccine is and again the all-important immune response. They also get an idea if the dosage that is delivered is work.

And then comes the final step, which is the Phase 3 trial – the biggest test of the experimental vaccine. Thousands of volunteers are given the vaccine to confirm its safety and immune response. Experts closely look for side-effects and how effective it is across the wide volunteer group. Interestingly, in this phase, a group of volunteers is given a placebo dose alongside the actual recipients.


Let’s now have a look at the labs at the forefront of the hunt for a stable Covid-19 vaccine.

One of the early contenders has been Chinese company CanSino Biologics. It has developed its coronavirus vaccine based on an adenovirus called Ad5. China-based CanSino did it with the support of the Institute of Biology at China’s Academy of Military Medical Sciences.

CanSino is running Phase 3 trials in a number of countries, including Saudi Arabia, Pakistan and Russia. For reasons of global politics, the CanSino vaccine has somewhat been less highlighted and hailed compared to the initiatives from labs of the Western world.

Then there’s the much debated Russian vaccine called Gam-Covid-Vac. Its trade name is Sputnik V – ‘V’ stands for vaccine and not the Roman numerical denoting ‘5’ as the western media has been reporting.

Sputnik V has been created by Gamaleya Research Institute, under the watchful eyes of Russia’s health ministry. It is a combination of two adenoviruses, Ad5 and Ad26, both engineered with a coronavirus gene. After Phase 3 trials, Gamaleya recently said its vaccine is 92% effective.

Quite like CanSino’s vaccine, Sputnik V has also been doubted and questioned to a good extent simply because it’s Russian-made.

Now let’s move on to the more talked about vaccines being developed by the West.

US-based Moderna is making a vaccine in partnership with National Institutes of Health. The Moderna vaccine’s Phase 3 trials began on July 27. In mid-November, Moderna announced that a preliminary study of the trial indicated that the vaccine was 94.5% effective.

The company has already made premeditated delivery deals with the US government, plus Canada, Japan and Qatar.

The coronavirus virus made by German company BioNTech, which will be marketed by New York-based Pfizer, is undergoing Phase 3 trials. The trials are taking place in the US, Argentina, Brazil, Germany and a few other countries.

In the second half of November, BioNTech and Pfizer said their vaccine is 95% effective. Pfizer has already applied for an emergency use authorisation.

And then, of course, a vaccine that the whole world is eagerly looking forward to is the one being developed by the University of Oxford in partnership with British-Swedish company AstraZeneca. Their vaccine is based on a chimpanzee adenovirus called ChAdOx1. Phase 3 trials are being held in the UK, India, Brazil, South Africa and the US.

In November, the vaccine maker said it is showing a robust immune response in healthy adults aged between 56 and 69, and those over 70.

Here in India, Bharat Biotech has created a vaccine called Covaxin in partnership with the ICMR (the Indian Council of Medical Research) and the National Institute of Virology. The vaccine is based on an inactivated form of the coronavirus. The vaccine’s Phase 3 trials began in October.

Some other key players also working on a breakthrough Covid-19 vaccine are Sanofi, SinoVac, Johnson & Johnson, Merck, Novavax and a few others.


As we all know, a vaccine basically stimulates the body’s immune system to create antibodies. So after getting vaccinated, a person develops targeted immunity to the disease in question.

The modus operandi of all the Covid-19 vaccines that scientists are working on is very interesting – it’s as if a high-end and highly sophisticated strategic war in progress.

This is how the vaccine will do its job. Once the vaccine enters the body, it replicates or makes exact copies of the spike proteins that the actual Covid-19 virus has.

This drill of cloning the spike proteins results in the human body reacting and producing antibodies – those antibodies that are trained and armed to attack Covid-19 viruses on sight.

Now, when the actual Covid-19 virus infects the individual and enters the body, antibodies that are already in place due to vaccination are ready to fire on all cylinders!  They catch hold the invading covornaviruses by surprise and disable them.

So, that’s how the Covid-19 vaccine will work in our bodies – standing guard like military hawks, waiting to pounce on the deadly virus.

The virus has tormented the world – from east to west, from the desperately poor to the mighty rich – for almost a year now. Are the greatest scientists of our times on the verge of winning the war against the invisible pathogen?

(Dr S A Siraj is a Kolkata-based doctor who has served as the Additional Director for Health Services in the state govt of West Bengal, India)

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