Zydus Cadila's COVID-19 vaccine okayed in India: From interval between doses to efficacy, here's what you must know

ZyCoV-D, a needle-free, three-dose COVID-19 vaccine by Ahmedabad-based  pharmaceutical major Zydus Cadila, has been okayed for emergency use in India. It becomes the sixth vaccine to get regulatory nod in the country of 1.3 billion people – after Serum Institute of India's Covishield, Bharat Biotech's Covaxin, Russia's Sputnik V, and the vaccines by Moderna and Johnson and Johnson (the last two are yet to hit the Indian market). ZyCoV-D also becomes the first vaccine for adolescents (12-18) to be approved in India. But when will it be included in the country's vaccination drive? What will be the prices? We try to answer some of your questions.When will it be available?According to Zydus Group managing director Sharvil Patel, supply could begin by mid-September or the end of September. Earlier, the company had said it would be ready for the vaccine rollout within 45 to 60 days of getting approval – which finally came on Friday. The company had applied for emergency use authorisation on 1 July.What is the interval between doses?The three-dose vaccine will be given on day zero, day 28th and then on the 56th day, according to the company official. In other words, there will be a four-week gap between the first and second doses as well as the second and third doses.How much will it cost?There is no clarity on that immediately. The company is working with government, and a decision could be taken within the next two weeks.What are the production targets?The company plans to manufacture 10-12 crore doses annually. One crore doses are expected by October, and four-five crore doses by the end of January 2022.Who all could take the shot?Adults, of course. Apart from them, adolescents in the 12-18 age group can take the vaccine. Around 1,000 adolescents were part of clinical trials that took place across 50 centres.Does this mean India can start inoculating children immediately?Not exactly. There are indications that vaccination of the adolescent population will start only after the government brings them within the inoculation ambit. At present, the national policy makes adults eligible for vaccination.How effective is the Zydus Cadila vaccine?The vaccine has shown a primary efficacy of 66.6% for symptomatic RT-PCR positive cases in the interim analysis. According to Zydus MD Patel, its efficacy against the highly contagious Delta variant too is 66%, news agency ANI reported.No moderate case of COVID-19 disease was observed among the beneficiaries after the third dose, suggesting 100% efficacy for moderate disease. The company says none of those who took part in the trials showed any serious severe adverse event. Phase 1 and interim Phases 2-3 clinical trial data have been published. Phase 3 full trials are yet to be completed.How does the vaccine work?ZyCoV-D is a plasmid DNA vaccine, which, when injected, produces the spike protein of the SARS-CoV-2 virus that causes COVID-19, and elicits an immune response mediated by the cellular and humoral arms of the human immune system. This plays a vital role in protection from disease as well as viral clearance.In other words, it means that the vaccine is manufactured by creating a close enough copy of the virus' DNA sequence (the technology ensures that this doesn't cause the disease in a human body). At the same time, the technology triggers an immune system response when the human body encounters the real virus the next time.Here are some other facts about ZyCoV-D.Needle-free: It is an intradermal vaccine, which is applied using The PharmaJet needle-free system.

• Needle-free injectors deliver the vaccine using a narrow stream of fluid to penetrate the skin and deliver the vaccine to the proper tissue depth.
• The company says this methodology can eliminate chances of needlestick injury and will also lead to a significant reduction in any kind of side effects. It will also help people suffering from trypanophobia, a common condition marked by an irrational fear of blood or needles. It's estimated that fear of needles affects up to 25 percent of adults.

Storage temperature: The prescribed storage temperature is between 2 and 8 degrees centigrade, but the vaccine has shown good stability at temperatures of 25 degrees centigrade as well for at least three months.

• The thermostability of the vaccine will help in easy transportation and storage of the vaccine and reduce any cold chain breakdown challenges leading to vaccine wastage.

The science behind: The plasmid DNA platform -- the vaccine is the first candidate to use such a technology against the Sars-CoV-2 virus -- provides ease of manufacturing with minimal biosafety requirements.

• It can be manufactured at a BSL-1 grade lab -- which brings down the cost of production and ensures that the cost of expanding production units.
• The Plasmid DNA platform also allows generating new constructs quickly to deal with mutations in the virus, such as those already occurring.