Around 13% have been fully vaccinated
India's drug regulator approved the emergency use of Covid-19's first DNA vaccine.
According to Cadila Healthcare, an interim study that was cited by vaccine maker Cadila Healthcare, 66% of those who received the three-dose ZyCoV–D vaccine were free from symptomatic diseases.
The firm intends to produce up to 120,000,000 doses of India’s second-home-grown vaccine each year.
Previous DNA vaccines worked in animals, but not in humans.
India has given more than 570 millions doses of three vaccines previously approved - Covishield and Covaxin - to date.
Around 13% of adults have been fully immunized, and 47% have had at least one shot since January's start.
Cadila Healthcare claimed it has conducted the largest Indian clinical trial of the vaccine, with 28,000 volunteers at more than 50 centers.
The firm also claimed that this is the first time that a Covid-19 vaccine has been tested on young Indians - 1,000 individuals aged 12-18. This age group found the jab to be safe and well tolerated.
At the height of the second wave of the virus's deadly second wave, the key third phase of clinical trial was completed. This, according to the vaccine maker, reaffirmed the jab’s "efficacy in combating mutant strains", particularly the highly infectious Delta variant.
"I'm very excited about this vaccine because it has a lot potential. "If this jab works, it will make the logistics of vaccination much easier," stated Prof Shahid Jameel. He is a well-known virologist.
What is the mechanism of this vaccine?
The building blocks of life are DNA and RNA. These molecules carry the genetic information that is passed from parents to their children.
A DNA vaccine is similar to other vaccines. Once administered, it teaches the body's immune systems how to fight the actual virus.
ZyCoV-D uses small DNA rings, or plasmids, to deliver the jab between the two layers of skin.
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The plasmids contain information that tells cells how to make "spike protein", which is what the virus uses to enter human cells.
The majority of Covid-19 vaccines are designed to instruct the body to make a small amount of the spike protein. This can trigger the immune system to produce antibodies to fight the virus.
What makes this vaccine unique?
This is the first ever human-derived DNA vaccine against Covid-19.
A number of DNA vaccines have been approved by the US for use in animals. These include a vaccine against a disease in horses, and a vaccine against skin cancer in dogs.
Vaccines
More than 160 DNA vaccines are currently being tested in clinical trials in the US. The majority of vaccines are for existing cancers. HIV was the third most commonly used.
ZyCov-D also marks India's first needle-free Covid-19 jab.
The fluid is administered using a disposable, needle-free injector that uses a narrow stream to penetrate the skin to deliver the jab to the appropriate tissue.
"To have a DNA vaccination that works against infection is huge." It should provide good protection, which is something India can be proud of," Dr Gagandeep Kang (virologist) said. She was also the first Indian woman elected Fellow of The Royal Society of London.
What are the benefits of a DNA vaccination?
Scientists believe DNA vaccines can be inexpensive, safe, and stable.
They can also be kept at higher temperatures, between 2 and 8C.
Cadila Healthcare claims their vaccine has shown "good stability" at 25C over at least three months. This would allow the vaccine to be easily transported and stored.
What are the downsides to a DNA vaccine?
In the past, DNA vaccines for human infectious diseases have failed.
They work well in animals, but they are not as effective in humans. Dr Kang said that they do not offer the same immune protection for humans.
Dr Kang said that the challenge was to get the plasmid DNA into a human cell in order to give an immune response.
Dr. Jeremy Kamil, a virologist from Louisiana State University Health Sciences Center, Shreveport, echoed a similar sentiment.
Plasmid DNA vaccines were tried in the past. Dr Kamil explained that it is very difficult to get the plasmid DNA in the nucleus human cells, particularly for adults.
mRNA vaccines, which use messengerRNA to make proteins, are not required to reach the nucleus. They offer greater efficacy, higher longevity, and a longer-lasting immunity.
ZyCoV–D, which requires three doses instead of the two required for the two other candidates in India, is another potential problem. According to the vaccine manufacturer, it is currently evaluating a two-dose jab.
"I would be thrilled if a vaccine company overcome the enormous challenges it faced to make it work." Dr Kamil said that it was crucial that efficacy data are independently verified.
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