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ZyCoV-D Could Be The Fourth COVID-19 Vaccine To Get Approval In India: All You Need To Know

ZyCoV-D is a new COVID-19 vaccine that is expected to hit the Indian vaccine market by June. The developer of the vaccine is an Ahmedabad-based leading pharmaceutical company Zydus Cadila.

According to reports, the vaccine has got the approval to start the trial by the Drugs Controller General of India (DCGI) along with Bharat Biotech's Covaxin last year in July, after they both were found safe in toxicity trials in rabbits, rats and mice. [1]

The vaccine is still under the phase 3 trial and could be India's first DNA vaccine-- unlike Covaxin that is a live-attenuated viral vaccine-- to be licenced for use in the country. Also, after Bharat Biotech's Covaxin, ZyCoV-d could be the second indigenous vaccine [2]

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The results of ZyCoV-D's first and second trials have been submitted and approved by the DCGI before the beginning of its third trial. However, the data have not been published and released to the public yet, creating doubt about its safety, effectiveness and efficacy.

The results of the third trial are expected to be submitted to DCGI by the end of May 2021, with plans to start the supply in June and begin further manufacturing of around 24 crore doses by the end of the year. The vaccine is known to be tested on over 28000 volunteers aged 12-99 years old.


What Is ZyCoV-D?

ZyCoV-D is a genetically engineered DNA-plasmid based vaccine, which is encoded with the membrane proteins of the COVID-19 virus, meaning the lab-modified DNA can behave like membrane proteins (spike proteins) of the virus that helps it enter the host cells.

According to a study, DNA vaccines are considered the most revolutionary approach to developing vaccines as they encode for the antigen (COVID-19 spike protein) and an adjuvant (immune cells) to trigger the adaptive immune response. [2]

According to COVID-19 vaccine tracker data, healthy individuals between 18-55 years were included in the phase 1 trials while those over 12 years for phase 2 trials. A total of 1,048 individuals were enrolled for both trials. [3]

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What Is Plasmid DNA Vaccine?

The plasmid DNA vaccine consists of both dead forms of the virus and molecules of antibodies or immune signal cells.

Usually, for the preparation of a vaccine, only the live-attenuated or inactive forms of the virus (like influenza vaccine) are taken, so that when it is administered, the body can trigger immunity specific to it. But sometimes, this leads to unpredictable behaviour of the immune system causing complications to humans.

To lower the risk of complications in ZyCoV-D a few molecules of adjuvant or immune cells are mixed along with DNA plasmids to help the body produce a stronger immunity without causing any complications. It also helps the immune cells to easily locate the virus.

The DNA-based vaccine could be the best vaccine type in the future due to the following reasons: [4]

  • The design includes the use of antigen-specific DNA to allow T-cells to target the antigen accurately.
  • Not only single, but the DNA could be genetically modified in many ways as per the mutation of the coronavirus to allow the body to produce a range of immunity. This technology can help prepare our body to fight against the mutated forms of the virus.
  • The beforehand delivery of molecular adjuvants can help the immune system tolerate the virus well and present no complication related to the virus intolerance.
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How DNA Vaccines Work

ZyCoV-D falls under the category of nucleic acid-based vaccine (DNA+RNA). The genetically engineered DNA is designed to match the DNA pattern of the virus, so as to stimulate the body to produce antibodies specific to COVID-19.

When the genetically modified vaccine is administered, the genetic material of a specific virus that is inside it, helps provide a steady supply of virus-specific protein, thus maintaining the steady supply of virus-specific immunity.

Further, the viral-genetic material in the vaccine is engulfed by the cells of the body, which then present the antigen of the virus (here COVID-19) to CD4+ and CD8+ T cells, immune cells which are responsible to identify, mark and trigger antibodies specific to antigens.

In this way, the DNA vaccine helps identify the antigen accurately to the body, so that our body can produce exact antibodies related to the antigen, and thus, kill it.

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ZyCoV-D Trial On Children

As per a news report, around 20 children between the age group 12-18 years have undergone first phase vaccine trials at Jeevan Rekha Hospital in Belagavi, Karnataka.

According to Dr Amit Bhate, Director of Jeevan Rekha Hospital, none of the children has reported any side effects or complications two months after the administration of the vaccine.

To mention, the hospital is also known to be one of the 12 centres in India where the trial of Covaxin took place successfully. [1]

According to doctors, those children are responding well to ZyCoV-D. Also, their blood samples and antibodies are checked regularly and will be for around a year, before making the vaccine available to children.

According to reports, ZyCoV-D trials on children are taking place at 30 different centres across India, with expected promising results.

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Why ZyCoV-D Could Be Different From Other Vaccines In India?

  • ZyCoV-D is a DNA-based vaccine compared to other mRNAs, adenovirus and protein subunit vaccines. [6]
  • It can provide no risk of infection as no live-attenuated virus is used for its development, unlike Covaxin and Covishield.
  • They are cost-effective.
  • ZyCoV-D is produced easily as it requires only BSL-1 labs, unlike other live-attenuated virus based vaccines (Covaxin) that require BSL-3 or BSL-4 labs. BSL-1 labs follow basic safety procedures and require no special design features or equipment.
  • It has good stability profiles compared to mRNA and protein-based vaccines.
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    Administration Of ZyCoV-D

    The vaccine is an intradermal injection, administered in the skin layer underneath the epidermis which is the upper skin layer. There will be three doses of the vaccine given on day 0, 28 and 56.

    Storage Of ZyCoV-D

    As per the data available to date, the vaccine could be stored at 2-8 degree-Celsius or even at 30 degree-Celsius for three months.

    This can help in vaccine distribution as it requires only a minimal cold requirement.

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    To Conclude

    The owner of ZyCoV-D Zydus Cadila is looking to scale up the production of the vaccine and is also exploring partnerships to help the manufacturing. As per the reports, the company is planning to start manufacturing vaccines with 10 million or one crore doses a month and then, double the capacity to 20 million or two crore doses a month.

Story first published: Saturday, May 22, 2021, 13:30 [IST]