ZyCoV-D is a DNA plasmid-based

COVID-19 vaccine A COVID19 vaccine is a vaccine intended to provide acquired immunity against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes coronavirus disease 2019 ( COVID19). Knowledge about the structure and fun ...

developed by

India India, officially the Republic of India, is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area; the List of countries by population (United Nations), most populous country since ...

n pharmaceutical company Cadila Healthcare, with support from the Biotechnology Industry Research Assistance Council. It is approved for emergency use in India.

Technology

The vaccine contains a DNA

plasmid A plasmid is a small, extrachromosomal DNA molecule within a cell that is physically separated from chromosomal DNA and can replicate independently. They are most commonly found as small circular, double-stranded DNA molecules in bacteria and ...

vector Vector most often refers to: * Euclidean vector, a quantity with a magnitude and a direction * Disease vector, an agent that carries and transmits an infectious pathogen into another living organism Vector may also refer to: Mathematics a ...

that carries the gene encoding the

spike protein In virology, a spike protein or peplomer protein is a protein that forms a large structure known as a spike or peplomer projecting from the surface of an viral envelope, enveloped virus. as cited in The proteins are usually glycoproteins that ...

SARS-CoV-2 Severe acute respiratory syndrome coronavirus 2 (SARS‑CoV‑2) is a strain of coronavirus that causes COVID-19, the respiratory illness responsible for the COVID-19 pandemic. The virus previously had the Novel coronavirus, provisional nam ...

. As with other DNA vaccines, the recipient's cells then produce the spike protein, eliciting a protective immune response. The plasmid also contains unmethylated CpG motifs to enhance its immunostimulatory properties. The plasmid is produced using ''E. coli'' cells. The vaccine is given as an intradermal injection using a spring-powered

jet injector A jet injector is a type of medical injecting syringe device used for a method of drug delivery known as jet injection. A narrow, high-pressure stream of liquid is made to penetrate the outermost layer of the skin (stratum corneum) to deliver me ...

. This is because successful

transfection Transfection is the process of deliberately introducing naked or purified nucleic acids into eukaryotic cells. It may also refer to other methods and cell types, although other terms are often preferred: " transformation" is typically used to des ...

of DNA vaccines requires traveling across both the cell plasma membrane and the

nuclear membrane The nuclear envelope, also known as the nuclear membrane, is made up of two lipid bilayer polar membrane, membranes that in eukaryotic cells surround the Cell nucleus, nucleus, which encloses the genome, genetic material. The nuclear envelope con ...

, and using a conventional needle gives poor results and leads to low immunogenicity.

Clinical trials

Pre-clinical trials

In February 2020, Cadila Healthcare decided to develop a DNA plasmid based

at their Vaccine Technology Centre (VTC) in Ahmedabad. The vaccine candidate was able to pass the pre-clinical trials on animal models successfully. A report of the study was made available via ''

bioRxiv bioRxiv (pronounced "bio-archive") is an open access preprint repository for the biological sciences co-founded by John Inglis and Richard Sever in November 2013. It was hosted by Cold Spring Harbor Laboratory (CSHL) until March 11, 2025, whe ...

'' and later published in the journal ''

Vaccine A vaccine is a biological Dosage form, preparation that provides active acquired immunity to a particular infectious disease, infectious or cancer, malignant disease. The safety and effectiveness of vaccines has been widely studied and verifi ...

''. Thereafter, human trials for Phase I and II were approved by the regulator.

Phase I and II trials

Phase I trials of the vaccine candidate started on 15 July 2020 and continued until October 2020. The vaccine candidate was tested on 48 healthy individuals in the 18–55 age range, with 28 days between each of the three doses. The trial found the vaccine to be "safe, well-tolerated and immunogenic". Cadila Healthcare began phase II trials of the vaccine candidate from 6 August 2021 with over 1,000 volunteers as part of the adaptive Phase I/II multi-centric, dose escalation, randomised, double-blind placebo controlled method. The company reported that phase II trials were completed by November 2020.

Phase III trials

In November 2020, the company announced it would test the vaccine candidate on about 30,000 patients in Phase III trials. In January 2021, the Drugs Controller General of India (DCGI) granted permission to conduct the Phase III clinical trials for 28,216 Indian participants in the 12–99 age group. Of this, about 1,000 individuals were in the 12–18 age group. Interim results from the phase III trials were made available in July 2021. On 1 July 2021, Cadila Healthcare reported the efficacy to be 66.6% against symptomatic COVID-19 and 100% against moderate or severe disease in its interim analysis of its phase 3 trial data.

Authorizations

On 1 July 2021, Cadila Healthcare applied to the Drugs Controller General of India (DCGI), seeking approval for Restricted Use in Emergency Situation for the vaccine. On 20 August 2021, the Subject Expert Committee of the Central Drugs Standard Control Organisation (CDSCO) recommended that the DCGI grant the approval, which the DCGI then granted on the same day.

Deployment

On 23 April 2021, production of the ZyCoV-D vaccine was started, with a yearly capacity of 240 million doses.

References

External links

* * {{DEFAULTSORT:ZyCoV-D Products introduced in 2020 Indian COVID-19 vaccines DNA vaccines