What’s Zydus Cadila’s ZyCoV-D? All you must know about world’s first plasmid DNA Covid vaccine

What is ZyCov-D Needle-Free Covid-19 Vaccine: India’s first Plasmid DNA Covid-19 vaccine, ZyCoV-D is in the fray seeking a nod for Emergency Use Authorization from the Drug Controller General of India (DCGI), Vaccine maker Zydus Cadila that already has anti-Covid treatments available in the market claimed to have conducted the largest clinical trial in India so far at over 50 centers and the participants included people between age group 12 and 18 years.

What are DNA vaccines and how they are different from mRNA vaccines?

According to World Health Organization, the DNA vaccine approach involves, “direct introduction of the vaccine 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.

Both the DNA and RNA vaccines although have the same goal as traditional vaccines, they work slightly differently. Unlike viral vector vaccines or inactivated vaccines as Covishield and Covaxin, the DNA and RNA vaccines use part of the virus’ own genes to stimulate an immune response

The difference between DNA and RNA vaccines is they are transmitted to another molecule that is called messenger RNA. Also, the DNA vaccine delivers the message via a small electrical pulse that pushes the message to the cell.

“Classic DNA vaccine when administered, after entering the body, it converts into RNA and mimics viral RNA structure and induces host immunogenicity while the mRNA vaccines are administered in viral genetic material form i.e. RNA itself. So basically mRNA vaccines are one step ahead of DNA vaccines. However, main human genetic material is DNA making DNA VACCINES safer to administer whereas mRNA vaccines may not be acceptable by host defense being foreign genome.” Dr. Shreoshi Saha, ESIC Hospital, explained talking to the Financial Express.

DNA and RNA vaccines are cost-effective and are being touted for effectiveness and ability to produce more quickly than traditional, protein vaccines. While traditional vaccines often rely on actual viruses, DNA and RNA vaccines can theoretically be made more readily available because they rely on genetic code–not a live virus or bacteria.

A paper published in the medical journal Frontiers in Immunology in 2019 reports that “preclinical and clinical trials have shown that mRNA vaccines provide a safe and long-lasting immune response in animal models and humans.”

Moreover, the DNA vaccines offer a number of potential advantages over traditional approaches that include stimulation of both B and T cell responses, improving the vaccine stability, says WHO.

Clinical trials and efficiency of ZyCoV-D

According to a statement by Zydus Cadila, both the Phase I/II and Phase III clinical trials have been monitored by an independent Data Safety Monitoring Board (DSMB). More than 1000 subjects belonging to age group 12 and 18 years in India participated in the trials and the vaccine was found to be safe and ‘very well tolerated’

The company further said that Zy-CoV-D has already established a robust immunogenicity and tolerability and safety profile with its 66.6 percent efficacy for RT-PCR positive cases in the interim analysis. No moderate cases of Covid-19 were observed in the vaccine arm post administration of thirds dose clocking a 100 percent efficacy for moderate disease, it further asserted.

The technology developed for the plasmid DNA platform vaccine, the company claims is easily adapted to deal with a mutation in the SARS-COV-2 virus, including those already existing.

ZyCoV-D vaccine administration and storage regime

The vaccine is currently following a three-dose regime but the company informed that it has also evaluated a two-dose regimen for ZyCoV-D vaccine using a 3 mg dose per dose and the immunogenicity results are promising, equivalent to the current three-dose regimen.

Unlike its peers, ZyCoV-D vaccine is applied through a needle-free system. Ideal temperature for storing vaccine is 2 to 8 degrees celsius, but has shown good stability at temperatures of 25 degrees for at least three months, claims the company, It’s storage requirements make it easier to transport and store shots without much wastage and reduce reliability on cold chain to some extent.