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What Do We Know About Zydus Cadila’s Made-in-India 3 Dose Vaccine?

Zydus’ ZyCoV-D could become India’s 2nd fully homegrown vaccine in use. Here’s what we know.

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<div class="paragraphs"><p>Zydus Cadila applies for emergency use approval for its COVID vaccine.&nbsp;</p></div>
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Zydus Cadila's three-dose COVID-19 vaccine, ZyCoV-D, has received emergency use authorisation (EUA) from the Drug Control General of India (DGCI), the Centre announced on Friday, 20 August.

The vaccine is the "world's first and India's indigenously developed DNA-based vaccine for COVID-19 to be administered in humans, including children and adults, 12 years and above," the Centre said in a statement.

Pharmaceutical company Zydus Cadila has applied for Emergency Use Authorisation for its COVID-19 vaccine with the Drug Controller General of India.

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Zydus Cadila conducted clinical trials for its COVID-19 vaccine across 50 centers. It is also the first vaccine to be tested on adolescents. Importantly, the phase 3 data of the vaccine is yet to be shared.

Because DNA vaccine is a considerably new technology, experts are not too convinced of its efficacy and safety without clinical trial data to back the claims.

"We have never had a licensed DNA vaccine for humans. I'd be very supportive but I would like to see the phase 3 data before thinking this is a valuable addition," Moneycontrol quotes Dr Gagandeep Kang, Virologist, Professor, Christian Medical College, Vellore in an earlier article.

How much do you know about the indigenous vaccine?

What kind of a vaccine is it? How does it compare to Covaxin and Covishield? When will we get it? FIT gets you up to speed on everything we know about the vaccine.

What type of vaccine is ZyCoV-D?

ZyCoV-D is a Plasmid DNA vaccine.

The DNA (And RNA) vaccines—a relatively new technology developed for the first time only in the 1990s—don't introduce a weakened form of the pathogen like traditional vaccines.

Instead, this type of vaccine works by carrying the genetic code of the virus. The plasmid vector is taken up into cells and transcribed in the nucleus. This is transferred to another mRNA molecule, which induces a cell-mediated immune response.

The Zydus vaccine is the first DNA vaccine to be produced in India.

In theory, DNA vaccines produce the same results as mRNA vaccines, and so the efficacy of the Zydus vaccine too is likely to be in the realm of the other mRNA vaccines already in the market, including Moderna, Pfizer, and Johnson & Johnson.

One advantage that DNA vaccines have over their mRNA counterparts is that they are more stable in higher temperatures, making them more suitable for use in warmer countries like India.

Furthermore, the (DNA vaccine) platform can be rapidly used to modify the vaccine in couple of weeks in case the virus mutates to ensure that the vaccine still elicits protection.

DNA vaccines work by introducing the genetic coding of the virus to the immune system to induce an immune response.
DNA vaccines work by introducing the genetic coding of the virus to the immune system to induce an immune response.
(Photo: NCBI)

At what stage is the vaccine?

In July of 2020, Cadila Healthcare Limited announced that their vaccine for COVID-19, named ZyCoV-D, successfully completed preclinical development and had received permission to initiate human clinical trials.

On 24 December, the company submitted the results of Phase I/II clinical trials conducted in over 1000 healthy adult volunteers.

On 3 January, they announced that their vaccine had received approval from the Drugs Controller General of India (DCGI) to start Phase III Clinical Trial of ZyCoV-D –

In their last statement, the company had informed that the dosing for the Phase III clinical trials took place across 50 locations, on 30,000 healthy adult volunteers.

How is it different from Covaxin and Covishield?

  • Zydus vaccine has the same goal, and is likely to have the same results as the two existing homegrown vaccines, but where it differs is in the way it works.

Covaxin is a whole inactive virus type vaccine, and Covishield is a non-replicating viral vector type vaccine.

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Both of which are relatively traditional, well established types of vaccine technology that work by introducing a part (in the Oxford vaccine it is the gene protein spikes found on the virus’ surface) or whole of the virus in a ‘harmless’ form to trigger the immune system into producing a large number of antigens to fight the actual virus.

The Zydus vaccine, as explained, is a DNA vaccine that delivers only a specific set of instructions to our cells that instructs our immune system to recognize and respond to the virus.

The Zydus vaccine is also India’s first plasmid DNA vaccine.

  • Unlike Covishield and Covaxin, ZyCoV-D is being tested as a 3 dose vaccine.

  • While it can be stored in normal refrigerator temperatures of 2 - 8 degrees Celcius like Covishield and Covaxin, the company also claims that the vaccine is very thermostable at up to 25 degrees.

How safe is it?

While Phases I and II of the trials showed no side effects, phase 3 data is yet to be shared publicly.

According to the Zydus group, “the Phase II study of the vaccine ZyCoV-D had been conducted in over 1000 healthy adult volunteers. The vaccine was found to be safe and elicit a strong immunogenic response”.

When will it be available?

If approved, according to Sharvil Patel, the company plans to begin production in June and launch the product in the market soon after.

The company aims to produce 5 crore doses by the end of the year and is also looking to ramp up production, if possible.

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