Categories: Vaccination

India to release world’s first DNA Vaccine for Covid-19

A recent news has brought a lot of cheer and hope to a world reeling under the Covid-19 pandemic. India’s drug regulator, The Central Drugs Standard Control Organization (CDSCO), has approved the world’s first DNA vaccine against the Covid-19 for emergency use.

It has brought back the debate about the efficacy of various vaccines currently available against the virus. To appreciate this, we first need to understand the different types of vaccines and how they work.

Types of Vaccines

Covid-19, like most notable viruses, including common cold, dengue, hepatitis, mumps, SARS, is a RNA virus. That is, the virus has RiboNucleic Acid (RNA) as its genetic material. Different approaches are taken to neutralize or destroy the virus. In general, the body’s immune system is programmed to generate the antibodies programmed to fight the viruses they encounter.

mRNA vaccine: Messenger RNA vaccines give instructions (hence messenger) to our body cells to make the spike protein of the infecting antigen, or at-least a part of it. The presence of the spike protein in the body cells is recognized by the immune system as an intruder, and is provoked into generating antibodies to fight the virus. Both Pfizer and Moderna vaccines for Covid-19 are of this type.
Viral vector vaccines: Here, a relatively harmless virus other than the infecting antigen, is introduced into the body. This acts as a messenger or vector and triggers the body cells to create the spike protein. Then, as explained previously, the body’s immune system produces antibodies to fight the viruses in the body. Oxford-AstraZeneca, Sputnik V and Johnson & Johnson’s vaccines for Covid-19 are of this type.
Inactivated Virus Vaccines: In this, dead viruses are introduced into the body antigens of which provoke the immune system to produce antibodies that fight off the virus. Since the viruses are dead, they don’t replicate in the body. This makes them safe for people with a compromised immune system. ronaVac, Sinopharm and Covaxin vaccines for Covid-19 are of this type.
Protein-based vaccines: In this, the spike protein of the coronavirus is replicated in a lab and introduced into the human body. Without the full virus, the spike alone is harmless. However, the body’s immune system treats this spike protein as an intruder and produces antibodies to fight the same. Novovax is a Covid-19 vaccine of this type.

Also Read: COVID-19 Vaccination: All Your Doubts Answered

What is a DNA vaccine?

DNA vaccines are relatively recent and take a new approach to fighting viruses as against the above conventional methods. DNA plasmids are circular pieces of DNA found in bacterial cells. These plasmids are harvested from certain bacteria and then encoded with the genetic sequence of the infecting antigen (coronavirus in this case). The encoded plasmids are then introduced in the human body in such a way that they reach the nucleus of cells. The body-cells then decode the sequence and in the process, create copies of the Coronavirus. The body’s immune system immediately recognizes an intruder and fights it constantly by producing antibodies.

ZyCov-D – World’s first DNA vaccine for Covid

Till date, many DNA vaccines have been introduced in the world to fight viruses such as HIV, as well as the cancerous cells in some types of cancers. They ae extensively used to fight disease in animals such as horses and dogs. However, there were no DNA vaccines to fight Covid-19 . All that is set to change now.

Cadilla Healthcare, a prominent Indian pharmaceutical company has launched the world’s first DNA vaccine against Covid-19 called ZyCov-D. This is a needle-free jab that is injected using a needle-free injector. This uses a narrow jet of the vaccine to penetrate the skin and reach specific tissues. Like J&J’s viral vector virus vaccine, inactivated virus vaccines and protein-based vaccines, this too can be stored at temperatures of 2 to 8 degree centigrade. This makes storage and transport convenient as all that is needed is an ice-box.

The vaccine has shown very good stability at 25 degrees centigrade which is the average outside temperature across India, for most parts of the year (except peak summer and peak winter). This makes storage and transport easy. That is why, India’s drug regulator has approved the vaccine for emergency use.

Drawbacks

While the news has brought cheer to the medical fraternity and the population at large, there are some skeptics too. According to Dr Gagandeep Kang, a virologist and the first Indian woman to be elected Fellow of the Royal Society of London, and Dr Jeremy Kamil, a virologist at Louisiana State University Health Sciences Center, DNA vaccines work very well with animals. In the past, they have been tried on human beings, but the immune response has not been significant. The main challenge is that it’s not easy to push DNA plasmids into the nucleus of a human cell, especially adults. That may be the reason this vaccine is being given in 3 shots as against 2 shots as with other vaccines.

The company has tested this vaccine on thousands of volunteers in the age-group of 12-18 years, and in as much as 66% of them, it could prevent a symptomatic infection of Covid-19. Further, this testing was done at the peak of the 2^nd wave, reiterating its efficacy against various mutants of the virus including the deadly Delta variant.

Outlook

India’s leadership in the battle against Covid-19 has been demonstrated yet again with the new DNA vaccine from Cadilla Healthcare. With time, the company may tweak the vaccine and increase its efficacy rates. This brings hope to millions of people across the world who are living under the shadow of the Covid-19 virus, and its newer variants that keep emerging from time to time.

Reviewed by Dr Suresh S Venkita, Group Medical Director, Kauvery Hospitals

Kauvery Hospital is globally known for its multidisciplinary services at all its Centers of Excellence, and for its comprehensive, Avant-Grade technology, especially in diagnostics and remedial care in heart diseases, transplantation, vascular and neurosciences medicine. Located in the heart of Trichy (Tennur, Royal Road and Alexandria Road (Cantonment), Chennai, Hosur, Salem, Tirunelveli and Bengaluru, the hospital also renders adult and pediatric trauma care.

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