India’s DNA vaccine is the first DNA vaccine for COVID-19. Find how it is made, the latest trial results, and when it will be available for the public.
What Is a DNA Vaccine?
We have already seen the various types of vaccines in our previous blogs and you can find them here. Diseases like the seasonal influenza virus, tetanus, polio, Hepatitis B, measles, mumps, rubella, cervical cancer, diphtheria, pertussis are usually prevented by DNA vaccines.
DNA vaccines are engineered to alter an individual’s genetic makeup. They code the DNA to identify antigens from a known virus and aid the immune system in producing antibodies following the detection of intrusions. They need to penetrate deep into the cell’s nucleus to be efficient whereas mRNA vaccines have to penetrate into the cytoplasm only.
Smallpox vaccine was the first DNA vaccine developed at the New York Department of Health by Enzo Paoletti and Dennis Panicali in 1983. These gene alterations pass on to the future generation too.
India’s DNA Vaccine
It is difficult to alter the DNA structure of an individual. DNA vaccines have so far been administered only on animals, especially horses. Most RNA and mRNA vaccine production were fast-tracked to provide the world with a cure for the pandemic. Therefore, only crucial aspects of the vaccines were analyzed during the clinical trial period.
Since DNA vaccines were not allowed for human trials, more than a dozen genetic vaccines are still under early trial stages. India and Japan’s vaccines have reached the last trial stage at present.
ZyCoV-D uses a circular plasmid strand in a promoter sequence to alter the gene structure. The vaccine was developed by Zydus Cadila, a pharmaceutical firm in Ahmedabad. The vaccine was tested on more than 28000 participants above the age of 12 following approval from India’s drug regulator. Zydus Cadila claims the trial showed around 67% efficacy but it has yet submitted a detailed report.
Advantages of DNA Vaccines
- Conventional vaccines trigger an immune response by either injecting an individual with a dormant virus or a specific genome from the pathogen. These methods may get ineffective if the virus evolves. DNA vaccines re-engineer the human cell to identify the core aspect of the virus that will never change regardless of the variant, making them more effective.
- These vaccines are easy to produce and cost-effective.
- Their stability results in easy storage and shipment. Booster shots are not necessary because they provide long-term protection.
Disadvantages of DNA Vaccines
- Since they alter the protein in the cell, they are not eligible for preventing infections caused by bacteria. Bacteria and parasites are often non-protein antigens.
- The injection-free vaccines introduced through a nasal spray can target brain cells leading to an unintended altercation in the brain.
- Generally, the same facilities are involved in developing various DNA vaccines. Thus, the risk of cross-contamination is high.
Why Is India’s DNA Vaccine Better?
Though ZyCoV-D has shown only 67% efficacy compared to other mRNA vaccines that have delivered more than 90% efficacy. Shahid Jameel, a virologist at Ashoka University in Sonipat, India, explained that the vaccine was developed after the Delta plus variant, unlike the mRNA vaccines that hit the market well before the Alpha variant. Thus, these vaccines should not be compared with each other.
How Will the ZyCoV-D be Administered?
DNA based vaccines are administered either through:
- Saline injection
- Gene gun
- Mucosal Surface delivery
- Polymer vehicle
- ELI Immunization
The skin is the primary area of infection. Thus, ZyCoV-D is delivered to rich immune cells by being deposited under the skin tissue. Trials have shown a minimum requirement of three doses to reach initial protection. India’s DNA vaccines are speculated to hit the Indian drug market soon.