ZyCoV-D: India's Homegrown Three-Dose Covid-19 Vaccine For Anyone Over 12, Approved For Emergency Use

The Ahmedabad-based pharmaceutical company Zydus Cadila has said that its Covid-19 vaccine has been approved for emergency use in India.

The announcement was made Friday evening (20 August).

The Drug Controller General of India (DCGI) has granted emergency use authorisation (EUA) for ZyCoV-D, the world’s first plasmid DNA vaccine for Covid-19, a statement said.

With this approval, India will have a vaccine that can be administered not just to adults but also to adolescents in the 12-18 years age group.

ZyCoV-D also becomes the second India-made vaccine, after Hyderabad-based Bharat Biotech's Covaxin, to receive regulatory approval.

Overall, it is the sixth vaccine to get approved in India, coming in after jabs developed by Moderna, AstraZeneca and Serum Institute of India, Bharat Biotech, Russia's Gamaleya Institute, and Johnson & Johnson.

ZyCoV-D is an intradermal vaccine that is administered over three doses — on days zero, 28, and 56.

The vaccine is delivered through a needle-free applicator and promises painless delivery.

Once introduced into the body, the vaccine is said to stimulate both the humoral and cellular arms of the adaptive immune system.

Like mRNA vaccines — the technology used by Pfizer-BioNTech and Moderna for their Covid-19 jabs — plasmid DNA vaccines have been under development since the 1990s.

DNA vaccines are known to offer several advantages. For one, they are considered to be safe and stable.

"As DNA vaccine plasmids are non-live, non-replicating and non-spreading, there is little risk of either reversion to a disease-causing form or secondary infection," scientists Michele A Kutzler and David B Weinersays write in an article about DNA vaccines for Nature.

These vaccines are also said to be "highly flexible, encoding several types of genes including viral or bacterial antigens, and immunological and biological proteins".

Because they are more temperature-stable than conventional vaccines, DNA vaccines can be relatively easily stored and manufactured on a large scale. They typically need minimal biosafety requirements too, as in the case of Zydus Cadila's vaccine.

ZyCoV-D is stored at 2-8 degree Celsius, but is said to display "good stability" at room temperature (25 degree Celsius) for at least three months. This makes it suitable for deployment even in remotes areas.

Furthermore, the vaccine can be modified in a span of couple of weeks in case of virus mutations, ensuring the vaccine can adapt and offer protection.

"The platform because of its rapid plug and play technology can be easily adapted to deal with mutations in the virus, such as those already occurring," Zydus Cadila said in a statement.

“This is a historic milestone with ZyCoV-D, a product of Indian innovation becoming the world’s first DNA vaccine being offered for human use and supporting the world’s largest immunization drive," Cadila Healthcare Ltd Chairman Pankaj R Patel has said.

ZyCoV-D has been developed in partnership with the Department of Biotechnology (DBT) under ‘Mission Covid Suraksha’, which is implemented by the public sector enterprise Biotechnology Industry Research Assistance Council (BIRAC).

Mission Covid Suraksha was launched by the Government of India, under the Aatmanirbhar Bharat package 3.0, in November 2020. It was conceived to accelerate the development of Covid-19 vaccines in India.

ZyCoV-D Milestones

A little over a year ago, Zydus Cadila had announced that its Covid-19 vaccine candidate was found to be safe and well tolerated in the Phase I clinical trial.

The Phase I trial had begun on 15 July 2020 after the vaccine was able to elicit high level of neutralising antibodies in animal studies previously.

On 6 August 2020, the Phase II trial involving over a 1,000 healthy adult volunteers took off. The study concluded at the end of the year, in December 2020, with the vaccine again demonstrated to be safe and immunogenic.

The company then initiated Phase III trials involving more than 28,000 volunteers and over 50 centres at the start of this year, in January 2021. Significantly, around 1,000 of these volunteers in the study were in the 12-18 years age group.

The vaccine was again found to be safe and well tolerated. It registered a primary efficacy of 66.6 per cent for symptomatic RT-PCR positive cases.

The company said in a statement that no severe cases or deaths due to Covid-19 occurred in the vaccine arm after administration of the second dose of the vaccine.

The clinical trials were monitored by an independent Data Safety Monitoring Board.

The same 1 July statement also announced that the company had applied to the DCGI for an EUA.

Over a month and a half later, on 20 August, the three-dose vaccine received the EUA.

What Next?

Managing director of Cadila Healthcare Dr Sharvil Patel had said in July that it would take 45-60 days after approval to launch the vaccine.

The company plans to manufacture 10-12 crore doses of the vaccine annually.

Zydus Cadila has, in parallel, evaluated a two-dose regimen for ZyCoV-D using a 3 mg dose per visit. Its immunogenicity results are said to be equivalent to that of the three-dose regimen. It also offers a reduced time frame to get "fully" vaccinated.

The company has said it plans to seek approval for its two-dose regimen as well.

Also Read: Bharat Biotech's Nasal Vaccine For Covid-19 Set To Advance Into Phase 2 Clinical Trial