Union Health Minister Mansukh Mandaviya.


Union Health Minister Mansukh Mandaviya.&nbsp | &nbspPhoto Credit:&nbspPTI

Key Highlights

  • Zydus has stated that its vaccine has an efficacy of 66.6 per cent based on an interim analysis of a late-stage clinical trial that involved over 28,000 volunteers, including 1,000 within the 12 to 18 age group, across 50 sites

  • The current vaccines in circulation in India are either inactivated virus vaccines or viral vector vaccines. Zydus' vaccine works in a similar way to the mRNA vaccines of Pfizer-BioNTech's and Moderna currently in use abroad

  • But DNA vaccines are believed to be more stable than their RNA counterparts owing to the presence of a substance called thymine. So while mRNA vaccines may facilitate cell instruction better than DNA vaccines, the latter is safer to administer

Addressing the Rajya Sabha on Tuesday, India's new Union Health Minister Mansukh Mandaviya defended the central government's handling of the COVID-19 pandemic, adding that efforts were being made to increase vaccine production and inoculate India's eligible population as quickly as possible. 

Referencing the 23,000 crore package to boost healthcare infrastructure, Mandaviya also called attention to the DNA-based COVID-19 vaccine developed by pharma major, Zydus Cadila and currently undergoing clinical trials.

“It is a matter of great pride for us that our scientists will be the first to develop a DNA vaccine,” he said.

The Ahmedabad-based pharmaceutical outfit announced at the start of this month that it had applied to the Drugs Controller General of India (DGCI) for emergency use authorisation of its ZyCoV-D three-shot COVID-19 vaccine. If granted approval, the vaccine will be the second indigenously-developed COVID-19 vaccine after Bharat Biotech's COVAXIN, the fifth vaccine to be approved in India, and notably, the world's first plasmid DNA vaccine. 

It will also be the first vaccine to have won approval after conducting trials on the 12 to 18 age group. The company is, reportedly, planning to produce 120 million doses of its 'needle-free' vaccine annually. 

Zydus has stated that its vaccine has an efficacy of 66.6 per cent based on an interim analysis of a late-stage clinical trial that involved over 28,000 volunteers, including 1,000 within the 12 to 18 age group, across 50 sites. 

“ZyCoV-D had already exhibited a robust immunogenicity and tolerability and safety profile in the adaptive Phase I/II clinical trials carried out earlier. Both the Phase I/II and Phase III clinical trials have been monitored by an independent Data Safety Monitoring Board (DSMB),” Zydus said via a statement. 

How do Plasmid DNA vaccines work?

According to the World Health Organisation, DNA vaccination 'involves the direct introduction into appropriate tissues of a plasmid containing the DNA sequence encoding the antigen(s) against which an immune response is sought, and relies on the in-situ production of the target antigen. This approach offers several potential advantages over traditional approaches, including the stimulation of both B-and T-cell responses, improved vaccine stability, the absence of any infectious agent and the relative ease of large-scale manufacture.' 

The current vaccines in circulation in India are either inactivated virus vaccines or viral vector vaccines. Zydus' vaccine works in a similar way to the mRNA vaccines of Pfizer-BioNTech's and Moderna currently in use abroad. 

These vaccines take a small portion of the virus' own genetic information – enough to trigger an immune response – inject them into cells which then produce the spike proteins to be recognised by the immune system. 

However, while both, DNA and RNA vaccines have the same goal, DNA is a two-stranded molecule while RNA is a single-stranded molecule. As such, the DNA molecule is more complex and needs to be converted into RNA which transmits instructions to the cell. 

But DNA vaccines are believed to be more stable than their RNA counterparts owing to the presence of a substance called thymine. So while mRNA vaccines may facilitate cell instruction better than DNA vaccines, the latter is safer to administer. 

What are its advantages?

Both, DNA and RNA vaccines are said to be safer to administer than vaccines developed using traditional approaches. This is because, unlike traditional vaccines, they do not involve growing the live virus before deactivating it. This is specifically important when it comes to the manufacturing process. Bharat Biotech's inactivated virus vaccine, for instance, requires a Bio-Safety Level 3 lab to be manufactured. Zydus,' on the other hand, can be produced in a BSL-1 facility, making it more cost-effective. 

Zydus' three-dose vaccine can also, reportedly, be stored at a temperature of between 2 and 8 degrees Celsius, making it a suitable candidate for storage across India's current cold-chain infrastructure. 

The company has also claimed that the vaccine was shown to remain stable at 25 degrees Celsius for as long as three months. Zydus has also stated that it is in the process of evaluating a two-dose regimen for its vaccine. 



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