India Gets World's First 'DNA-Based' COVID Vaccine: All You Need To Know About ZyCov-D

Indian drug regulator DCGI on Friday, August 20, approved vaccine maker Zydus Cadila's three-dose COVID vaccine ZyCoV-D for emergency use in adults and children aged 12 years and above. It has become the sixth vaccine authorised for use in India so far and the only needle-free COVID vaccine in the country.

With this, India has now approved its maiden vaccine for children, a much-needed decision amid looming threats of the possible third wave in the country, which some experts have opined could be deadlier towards children. Reportedly, the DNA vaccines have so far worked well in animals but it has not shown remarkable results in humans.

While the Union Health Ministry has denied that the next wave of COVID-19 would prove more dangerous to the 'vulnerable and unvaccinated' population especially children, it has, at the same time, augmented paediatric services across the country as a preventive measure. The company has already started stockpiling vaccines and said it plans to manufacture 100 million to 120 million doses yearly.

As soon as the approval came from DCGI, Prime Minister Narendra Modi and Union Health Minister Mansukh Mandaviya took to their respective Twitter handles and lauded the country's efforts against the pandemic.

"India is fighting COVID-19 with full vigour. The approval for world's first DNA based 'ZyCov-D' vaccine of @ZydusUniverse is a testimony to the innovative zeal of India's scientists. A momentous feat indeed," Modi tweeted.

The generic drugmaker, listed as Cadila Healthcare Ltd, applied for the authorisation of ZyCoV-D on July 1, based on an efficacy rate of 66.6 per cent in a late-stage trial of over 28,000 volunteers nationwide, reported News18.

"Interim results from Phase-III Clinical Trials, in over 28,000 volunteers, showed primary efficacy of 66.6 per cent for symptomatic RT-PCR positive cases," a government release said. It added that this has been the most prominent vaccine trial to date in the country for COVID-19.

"The vaccine had already shown robust immunogenicity and tolerability and safety profile in the adaptive Phase I/II clinical trials carried out before. Both the Phase I/II and Phase III clinical trials have been monitored by an independent Data Safety Monitoring Board (DSMB)," it added.

"I am thrilled about the vaccine because it has a lot of potential. If it works, the future of immunisation becomes logistically simpler," one of the reputed virologist Prof Shahid Jameel said, as quoted by BBC.

How Does It Function?

Both DNA and RNA are considered the building blocks of life. They are molecules that carry genetic information from one generation to another. Once administered into the body, a DNA vaccine, like the previous vaccine, signals the body's immune system to fight the virus. ZyCoV-D makes use of plasmids or small DNA rings containing genetic information to deliver the jab between two layers of the skin. The plasmids then transmit information to the cells in order to make the "spike protein". The virus uses it to latch on and enter the cells of human beings.

How Is It Different?

Unlike other vaccines produced globally, this is the first human DNA vaccine against the deadly COVID-19 virus. Although the US has approved some DNA-based vaccines in the past for animals, this is the first one to be put in use for humans, BBC reported. Apart from the COVID vaccine, the US is also testing more than 160 different DNA-based vaccines to treat existing cancers and HIV.

ZyCov-D is delivered with a disposable needle-free injector. It uses a narrow fluid stream to penetrate the skin and administer the vaccine to the proper tissue.

"It is a big deal to have a DNA jab which is effective against COVID-19. If it gives the desired results, this is something the country will be proud of," said Dr Gagandeep Kang, as quoted by BBC. Kang was the first Indian woman virologist to be elected Fellow of the Royal Society of London.

Pro's And Con's Of DNA Vaccine

As per the scientists, DNA vaccines are considerably cost-friendly, safer, and stable. Unlike other vaccines, they can be stored at higher temperatures from - 2 to 8 degrees Celsius. Cadila Healthcare claims that the vaccine had shown "good stability" at 25 degrees for a period of three months, which would help transport and store it easily.

However, scientists say that DNA vaccines for infectious diseases among humans could be less effective considering the past trials. "In a human body, they don't tend to offer the same level of immunity as in animals," said Dr Kang.

According to her, the challenge was to put the plasmid DNA into the human cell to look for a durable immune response.

"Plasmid DNA vaccines have been tested previously. But we are aware it's quite difficult to get plasmid DNA into the nucleus of human cells," Dr Jeremy Kamil, a virologist at Louisiana State University Health Sciences, told BBC.

Like other vaccines, which require a maximum of two doses, ZyCoV-D requires three doses, which is also considered one of the potential drawbacks. However, the makers said that they are evaluating at a two-dose jab.

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