ZyCOV-D: 10 Things You Should Know About World’s First Plasmid DNA COVID-19 Vaccine

Vaccine ZyCov D gets nod
ZyCOV-D Vaccine: Zydus Cadila, the Ahmedabad-based pharmaceutical company has applied to the national drugs regulator, CDSCO (Central Drugs Standard Control Organisation) for the approval of its COVID-19 vaccine ZyCOV-D. The company has sought Emergency Use Authorisation (EUA) for the said vaccine.

It would be the world’s first DNA vaccine against SARS-CoV-2 if approved. The vaccine has been developed with the support of the central government’s Department of Biotechnology and the ICMR (Indian Council of Medical Research).

10 Important things to know about ZyCOV-D

1. What is ZyCOV-D vaccine? How does it work?

ZyCOV-D is a “plasmid DNA” vaccine. That is, it uses a genetically engineered , non-replicating version of a type of DNA molecule called a “plasmid”. Here, the plasmids are coded with the instructions to make the spike protein of SARS-CoV-2 (the Coronavirus causing COVID-19). Vaccination gives the code to cells in the recipient’s body. Then they can begin to make the spiky outer layer of the virus. The immune system is expected to recognise it as a threat and develop antibodies by way of response.

2. How many doses of the vaccine are required?

While most COVID-19 vaccines are given in two doses, the plasmid vaccine will be given in three doses, with an interval of 28 days between the first and second and second and third shots. Another unique feature of the vaccine is that no needle is used in injecting it. Instead, it is a spring-powered device that delivers the shot as a narrow, precise stream of fluid which penetrates the skin.

3. Is the vaccine safe and effective?

The vaccine has been tested in phases 1, 2 and 3 clinical trials that involved over 28,000 participants. Several of these participants were aged between 12 and 18 years. The first two phases of the trial revealed the vaccine to be safe and immunogenic. Two doses of it appear to be enough to keep away severe symptoms and death while three doses prevent mild symptoms too.

4. Effect on Delta variant

The large scale phase 3 trial of ZyCOV-D took place at 50 clinical trial sites across the country when the second wave of the pandemic was at its peak. The tests have reaffirmed the effectiveness of the vaccine on the Delta variant as most strains found in the surveillance tests happen to be Delta variant.

5. How effective is the vaccine on other variants?

The company can upgrade the vaccine if required to target other variants of interest and variants of concern which can become more infectious or virulent in nature. Makers of the vaccine are presently “making the constructs” for studying its current effectiveness in neutralising the variants.

6. Does the vaccine affect one’s health in any way?

Public health activists have pointed out that so far, not much evidence has been found regarding the safety and immunogenicity (ability to prompt an immune response) on the vaccine’s safety. Though some safety concerns have been raised about the potential of DNA vaccines historically, researcher Dr Margaret A Liu said in a 2019 article, “To date, both pre-clinical testing and careful clinical monitoring have shown DNA vaccines to not induce or to worsen auto-immunity…”.

7. Non infectious vaccine

The DNA vaccine is “non-infectious” by nature. It does not involve the use of any potentially harmful particles such as viral vectors. Thus, the risk of vaccine enhanced diseases is reduced.

8. Procedure for approval

The regulator will go through the application of the manufacturer’s application for restricted emergency use permission and check if there is any information that’s missing. Thereafter, a meeting of the Subject Expert Committee (SEC) of the CDSCO will be called. During the meeting, the company will present the data and make its case for an EUA. Based on the data and other details, the SEC will decide whether or not to approve the vaccine.

9. By when will the vaccine be available if approved?

Ample doses of the vaccine are expected to be ready the end of July, 2021 and the production is expected to begin by mid-August. The company will be producing 10 million doses every month and hopes to provide the country with 50 million doses by December.

10. What will be the cost of the vaccine?

The cost of ZyCOV-D has not been decided yet.

Image source: Kannada Prabha