World’s first DNA Covid vaccine

Zydus Cadila, the Ahmedabad-headquartered pharmaceutical company, has approached Drug Controller General of India (DCGI) for restricted emergency approval for ZyCov-D, its three-dose Covid-19 vaccine. If approved for use, this would be the world’s first DNA vaccine against Covid-19.

What is the ZyCov-D vaccine, and how does it work?

  • ZyCov-D is a “plasmid DNA” vaccine — or a vaccine that uses a genetically engineered, non-replicating version of a type of DNA molecule known as a ‘plasmid’.
  • The plasmids in this case are coded with the instructions to make the spike protein of SARS-CoV-2, the coronavirus that causes Covid-19. Vaccination gives the code to cells in the recipient’s body, so they can begin making the spiky outer layer of the virus. The immune system is expected to recognize this as a threat and develop antibodies in response.
  • Most Covid-19 vaccines currently are given in two doses, with a couple of single-shot ones also available. ZyCov-D by contrast, will be given in three doses, with an interval of 28 days between the first and second and second and third shots.
  • The other unique thing about the vaccine is the way it is given. No needle is used — instead, a spring-powered device delivers the shot as a narrow, precise stream of fluid that penetrates the skin.
  • ZyCov-D has been developed with the support of the central government’s Department of Biotechnology and the Indian Council of Medical Research (ICMR).

How safe and effective is the vaccine?

  • ZyCov-D has been tested in phase 1, 2 and 3 clinical trials involving over 28,000 participants in all. A thousand of these participants were of ages between 12 and 18 years.
  • According to trial data so far, 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.