ZyCoV-D: the plasmid vaccine

Zydus Cadila a homegrown healthcare and pharmaceutical major, has applied for emergency use authorization (EUA) to the Drug Controller General of India (DCGI) for ZyCoV-D, which is a plasmid DNA vaccine to curb Covid-19.


ZyCoV-D comes under the category of ‘nucleic acid’ vaccines. It uses a genetically engineered vaccine, that are coded with direction to spike proteins of SARS-CoV-2. On vaccination this codes function within the recipient’s body is to make spiky outer layer of the virus thus eliciting an immune response by the production of antibodies for protection and fight against the virus.


The company states that they have conducted clinical trials around 50 centers across the country.

Dr. Sharvil Patel, MD, Cadila Healthcare Ltd, said that the adaptive Phase I/II clinical trial conducted earlier had shown promising result, exhibiting a robust immunogenicity, tolerability and safety profile.


Phase III trials have been conducted with over 28,000 volunteers across India. Moreover, it was the first time any Covid-19 vaccine had been tested on adolescent kids in the age group of 12-18 years.


“Around 1,000 subjects were enrolled in this age group and the vaccine was found to be safe and very well tolerated. The tolerability profile was similar to that seen in the adult population,” said Sharvil Patel at a briefing.

Both the Phase I/II and Phase III clinical trials have been monitored by an independent Data Safety Monitoring Board (DSMB).

“This breakthrough marks a key milestone in scientific innovation and advancement in technology. As the first ever plasmid DNA vaccine for human use, ZyCoV-D has proven its safety and efficacy profile in our fight against COVID-19. The vaccine, when approved, will help not only adults but also adolescents in the 12 to 18 years age group,” Dr. Patel said.

It was observed that no serious case or death have been reported since the second dose of vaccine has been administered. There vaccine has attained a primary efficacy of 66.6% for symptomatic RT-PCR positive cases in interim analysis. No moderate case of COVID-19 disease was observed in the vaccine arm post administration of the third dose, which suggests 100% efficacy for moderate disease




The company said it had evaluated a two-dose regimen for ZyCoV-D vaccine using a 3 mg dose per visit, and the immunogenicity results had been found to be equivalent to the current three-dose regimen.

The vaccine will come with Pharmajet, a needle free applicator that determines pain free intradermal vaccination. Albeit it would cost more, the company has yet to disclose the vaccine or the applicators price.

The needle free applicator would help to decrease the full course vaccination duration, simultaneously sustaining the high safety profile of the vaccine in the future.

They can be manufactured easily as it requires minimal biological safety levels (BSL-1) unlike attenuated vaccines (for example small pox vaccine etc.) which require the top BSL-3 or BSL-4 units.


Zydus Cadila, till date have made an investment of Rs500 crore for the vaccine project, including the current production unit and had planned on producing 10-12 crore doses annually once it gets regulatory approval. The gap between two doses (first and second dosage) is 28 days.