World’s first vaccine for children, ZyCoV-D, developed by the Ahmedabad-based Zydus Cadilla group, in partnership with the Department of Biotechnology under the ‘Mission COVID Suraksha’, was approved by the Drug Controller General of India for emergency use on August 20, 2021. The vaccine can be administered to adults as well as those who are 12 and above. The company is expected to make 10–12 crore doses annually and five crores by the end of this year. It happens to be India’s first vaccine for 12–18 age group, but sixth in the pack of vaccines for adults. Moreover, it is the second indigenous vaccine after Covaxin.
Salient Features of the Vaccine
- ZyCoV-D is the world’s first DNA-based vaccine for COVID-19 developed by an Indian company.
- It is a 3-dose course, with 28 days gap between each shot.
- It is to be administered with a needle-free applicator known as PharmaJet as opposed to a syringe, in order to reduce the chance of side-effects and pain.
- Unlike mRNA vaccines, DNA-based vaccines do not require ultra-cold storage systems, and can be stored at 2–8 °C that is best suited for India’s cold storage requirement. It also shows good stability at 25 °C for at least three months. Hence, it is more cost-effective and easy for transporting supplies to remote locations.
- It can be manufactured with minimum biosafety requirements because its manufacturing facility does not require the setting up of BSL-3 high containment facility compared to the production of inactivated virus vaccines such as Covaxin.
- It uses a section of genetic material from virus (SARS–CoV-2) that gives instructions as either DNA or RNA to make the specific protein, recognised and responded to by the immune system. When the DNA plasmid is injected into the human cell, it enters the nucleus and starts reproducing spike proteins, leading to the generation of antibodies. Therefore, the ‘plug-and-play’ technology, on which the plasmid DNA platform is based, can be easily adapted to deal with mutations in the virus, such as those already occurring.
- Interim results of clinical trials of Phase III on over 28,000 volunteers, the largest vaccine trial so far in India for COVID-19, showed a primary efficacy of 66.6 per cent for symptomatic RT-PCR positive cases.
- All the three trials have been monitored by an independent Data Safety Monitoring Board (DSMB).
Other Approved Vaccines and Their Efficacy
ZyCoV-D is the fifth vaccine to be approved for use in India—the other four being Covishield by Serum Institute of India (70 per cent effective), Covaxin by Bharat Biotech (77.8 per cent), Sputnik V by Gamaleya Research Institute (Russia) (97.6 per cent), and Moderna or mRNA-1273 by Moderna Inc. (US) (94.1 per cent).
Covishield and Covaxin still continue as the mainstay of India’s vaccination programme even after nearly 57 crore doses have been administered. The single-dose vaccine, Janssen, developed by Johnson & Johnson, (with efficacy of at least 50 per cent) has also received emergency use authorisation (EUA), but it is not being used in the vaccination drive.
Nearly 90 per cent vaccination has been done with Covishield. About a third of adults have been administered at least one dose and 10 per cent two doses.
Biosafety Level 3
Biosafety is an important concern in every biomedical and medical setting throughout the world. There is an increasing need of instituting biosafety and biosecurity norms/measures because of the possible dual use of microbial pathogens and increasing awareness. Biosafety level 3 (BSL-3) is related to clinical, diagnostic, teaching, research, or production facilities where such agents are used as may cause serious or lethal disease through inhalation, to the personnel, or that may contaminate the environment.
BSL-3 requires that laboratory personnel receive specific training in handling pathogenic and potentially lethal agents, and be supervised by scientists competent in handling infectious agents and related procedures.
Conclusion
The first DNA-based vaccine against COVID-19 is a revolutionary step. According to the World Health Organization, the technology involves direct introduction of plasmid containing the DNA sequence encoding the antigen against which an immune response is sought. The technology has many benefits over the traditional methods of vaccine development. It can stimulate both B and T-cell responses, improve vaccine stability, not infections, and facilitate mass-production.
The approval of ZyCoV-D will play a significant role in immunising children between the age group of 12–18.
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