Zydus Cadila’s Covid-19 vaccine: How it compares with peers, manufacturing capacities and challenges, explained

 Status of development

Sources told Moneycontrol that ZyCoV-D has completed dosing of participants in its Phase 3 trial and the process of data analysis is underway. The company is testing the vaccine on around 28,216 volunteers of over 12 years of age across 60 clinical trial sites. The CTRI website shows that recruitment is still underway.

Zydyus Cadila had earlier said it anticipates a clinical trial readout in the first quarter of FY22. This will be based on 158 events of Covid-19. The company said its vaccine was found to be well tolerated and immunogenic in the Phase I/2 clinical trials. In the Phase 2 study, ZyCoV-D had been tested on over 1,000 healthy adult volunteers.

 Manufacturing capacities
The company is setting up a manufacturing plant to produce 120 million doses of ZyCoV-D a year. Zydus Cadila said the plant is expected to be ready for commercial production by the first quarter of FY22. In addition, the company is also looking at possible tie-ups with partners to add another 60-70 million doses, with a target production capacity of 200 million doses.

Zydus Cadila has invested Rs 150-250 crore on both R&D and manufacturing of the Covid-19 vaccine. The company says scaling up of manufacturing will not be a big challenge as its Covid-19 vaccine is easily replicable and scalable, requiring just Biosafety Level (BSL)-1, as it does not use a live virus. Covaxin, for instance, requires BSL-3 facilities. Biosafety level-1 applies to laboratory settings and manufacturing plants in which personnel work with low-risk microbes that pose little to no threat of infection in humans. Novel approach Zydus Cadila has taken a novel approach for its potential Covid-19 vaccine. Called plasmid DNA, the vaccine consists of genetic material of SARS-CoV-2 proteins, which instruct human cells to make SARS-CoV2 antigen, eliciting an immune response. The company says that this approach is easily replicable and scalable, requiring just Biosafety Level (BSL)-1. The vaccine can be stored at 2-8 degrees temperature, making it conducive for Indian cold-chain conditions. The vaccine is delivered through the intradermal route (between the layers of the skin), which makes its administration much easier. Challenges
Firstly, the platform is novel. Not a single vaccine using this platform has been approved anywhere in the world. The other big challenge is that the vaccine has to be administered in three doses, at day 0, day 28 and day 56. Being a three-dose vaccine adds an additional layer of distribution and administration complexity, possibly raising the cost of the vaccine. The company has promised to ensure the vaccine is affordable.

Serum Institute of India (SII)’s Covishield, Bharat Biotech’s Covaxin and Russia’s Sputnik V, approved in India for emergency use, are all two-dose vaccines.

Comparison with other Covid-19 vaccines

ZyCoV-D is based on the DNA platform, which is new even for drug regulators. Other vaccines, such as Covishield, Sputnik V  and Covaxin, are based on the established viral vector and inactivated platforms.

ZyCoV-D has to be given in three doses, which adds complexity in terms of  distribution and administration compared to other vaccines, which need to taken in two doses (Johnson & Johnson's vaccine is a single-dose shot).

But if Zydus Cadila is able to crack the DNA platform technology, then scaling up isn't going to be a problem, say the experts, as DNA vaccines do not require BSL-3 containment facilities in their manufacture. This reduces the time to scale up and makes it less capital intensive.

DNA vaccines are also theoretically easy to redesign quickly against a mutating virus.  The vaccine is delivered through the intradermal route (between the layers of the skin), which makes its administration much easier, compared to other vaccines, which are based on intramuscular route.