All you need to know about ZyCoV-D vaccine

The vaccine has been approved for a three-dose regimen, but the company is likely to submit more data to the Drug Controller General of India (DCGI) for a two-dose regimen
Beneficiaries in the above-18 age group get inoculated against Covid-19 at a vaccination centre in Vile Parle (East). (HT PHOTO)
Beneficiaries in the above-18 age group get inoculated against Covid-19 at a vaccination centre in Vile Parle (East). (HT PHOTO)
Published on Aug 26, 2021 01:08 AM IST
Copy Link
ByJyoti Shelar, Mumbai

Ahmedabad based pharmaceutical company Zydus Cadila received the Emergency Use Authorisation (EUA) for its Covid-19 vaccine called ZyCoV-D last week. It is the first vaccine approved for children above 12 years. The vaccine has been approved for a three-dose regimen, but the company is likely to submit more data to the Drug Controller General of India (DCGI) for a two-dose regimen. What’s needle-free technology? What is a DNA-based vaccine? And when will we know about the vaccine’s phase 3 trial data? (A company press release from last month, interim results of Phase 3 revealed a 66.6% primary efficacy.)

Plasmid DNA technology used

With ZyCoV-D, there are now six vaccines permitted for use in India although only three are currently in use.

ZyCoV-D, developed in partnership with the Department of Biotechnology has been made on the Plasmid DNA platform. Plasmids are ring-like pieces of DNA that self-replicate. They are modified to encode the antigen or spike protein of the Sars-CoV-2, which are delivered inside the cell of the human body, prompting the production of more such proteins. This in turn triggers an immune response from the body forming antibodies against Covid-19.

How it’s different from the other vaccines

Oxford-AstraZeneca’s Covishield and Gamaleya Scientific Research Institute’s Sputnik V use a viral vector platform or an adenovirus (like the common cold virus) modified to encapsulate the genetic code of the Sars-CoV-2 spike protein, while Bharat Biotech’s Covaxin is an inactivated Sars-Cov 2 virus, which once injected, triggers an immune response. Johnson & Johnson’s single-dose vaccine (which will be made by Hyderabad-based Biological E) is also a viral vector vaccine while Moderna – which Cipla was permitted in June to import – uses the messenger Ribonucleic Acid or mRNA platform, in which the genetic code of a single spike protein of the Sars Cov-2 virus is injected into the body, prompting the cells to make more of it thus triggering an immune response.

Intra-dermal, needle-free vaccine

The three vaccines currently available are all for the adult population and are intramuscular, meaning the vaccine is injected into the muscles. ZyCoV-D is an intradermal Covid-19 vaccine that is delivered into the dermis or the layer right under the upper layer of the skin (the epidermis). While other intradermal vaccines like the BCG vaccine use needles, ZyCoV-D is a needle-free vaccine administered with the help of a needle-free applicator. The applicator pushes a small quantity of the vaccine into the skin at very high pressure. “The applicator is calibrated for a 0.1 ml dose, and it is delivered within a fraction of a second,” said Dr Ramesh Bharmal, dean of Mumbai’s BYL Nair Hospital where a ZyCoV-D trial is ongoing. The hospital has a target to enroll 50 adolescents but has so far managed to get only 11 candidates. “None of them have complained of pain. The applicator makes a sound at the time of administering the vaccine. All the children said they were distracted with that sound, and didn’t realise that they received any injection,” said Bharmal.

Some studies state that needle-free jet injections can improve the delivery of DNA vaccine compared to a standard needle injector. The needle-free technology also reduces needle injuries as well as waste.

Trial data yet to be made public

The interim results of ZyCoV-D from the Phase 3 clinical trials with over 28,000 volunteers have shown primary efficacy of 66.6%, a company press release stated last month. Around 1000 of these volunteers were in the age group of 12 to 17 years. These findings have been submitted to the Drugs Controller General of India (DGCI), based on which EUA was granted to the vaccine. However, the data is yet to be published or made available publicly. The Hindustan Times reached out to Zydus Cadila to know the likely schedule of phase 3 data publication but did not receive a response. “It is ideal to have the data published before any kind of approvals are granted by the drug regulator,” said immunisation expert Dr Naveen Thacker. “But we are in a war-like situation in this pandemic and it is understood that the subject expert committee has done a fair scrutiny of the data before granting the approval.”

Can it be used on children?

Zy-CoV-D is the first vaccine to be approved for use in children above the age of 12 in India. According to a press release by Zydus Cadila dated July 1, the vaccine was tested on 1000 children between 12 and 18 years and was found to be “safe and very well tolerated”. “Since it’s a new technology, the vaccine should be first administered to a large number of the adult population to know the side effects that may have been missed during the trial phase,” said paediatrician and infectious disease expert Dr Tanu Singhal, who practices at Kokilaben Dhirubhai Ambani Hospital in Mumbai.

SHARE THIS ARTICLE ON
Close Story
SHARE
Story Saved
OPEN APP
×
Saved Articles
Following
My Reads
Sign out
New Delhi 0C
Monday, November 29, 2021