How Is Zydus Vaccine Different From Other COVID-19 Vaccines?

Zydus Cadila, an Ahmedabad-based pharmaceutical company has applied to Central Drugs Standard Control Organisation seeking emergency-use authorisation for its three-dose covid-19 vaccine ZyCoV-D.

If approved by CDSCO, ZyCov-D will be the world’s first DNA vaccine against infection with SARS-CoV-2.

How is the Zydus vaccine different?

ZyCoV-D is a three-dose vaccine that uses a genetically engineered, non-replicating version of a type of DNA molecule known as a ‘plasmid’. It spikes the protein of the SARS-CoV-2 and elicits an immune response mediated by the cellular (T lymphocytes immunity) and humoral (antibody-mediated immunity) arms of the human immune system.

How does it work?

While the currently available vaccines are given in two doses, ZyCov-D will be given in three doses within an interval of 28 days between three shots. Another feature of the vaccine is that it would be needle-free. Reportedly, a spring-powered device will deliver the shot as a narrow, precise stream of fluid that penetrates the skin and this system can lead to a significant reduction in side effects.

What is ZyCoV-D’s efficacy against COVID-19?

Zydus claims the vaccine has been tested in over 50 centres in the adolescent population between 12 and 18 years, a first for any COVID-19 vaccine. Around 1,000 subjects were enrolled in this age group and the vaccine was reportedly found to be safe.

Primary efficacy of 66.6% has been attained for symptomatic RT-PCR positive cases in an “interim analysis". After administration of the second dose of the vaccine, there were no severe cases or deaths due to COVID-19 that occurred in the vaccine arm, as per reports.

As per the data acquired from the trial, the vaccine has been able to bring down symptomatic cases of COVID-19 in those who received doses by nearly 67 per cent compared with those who did not get a vaccine.

How many doses of ZyCoV-D can the company produce?

Zydus plans to manufacture 100-120 million doses of ZyCoV-D per year. The pharma company will be manufacturing the ZyCoV-D at its plant at the Zydus Biotech Park in Ahmedabad. According to Zydus Group chairman Pankaj R Patel, the system is expected to be ready by the end of this month, and production might begin by mid-August.

What are the concerns with the vaccine?

Reportedly, Public health activists have mentioned that little scientific evidence from the human clinical trials has been published on the vaccine’s safety and immunogenicity to date.

Previously, safety concerns have been raised about DNA vaccines, including their potential, theoretically, to integrate into cellular DNA or cause auto-immune diseases.

According to Indian Express, Dr Sharvil Patel, Zydus Cadila Managing Director,  said that the company has submitted data from phase 1 clinical trials of ZyCov-D, and this is “almost” ready to be published on a preprint server for peer review. The preparation for phase 2 data publication is being done and data from the phase 3 trial will take another four to six months.