ZyCoV-D, first DNA vaccine approved

India has approved the second in-house manufactured vaccine, developed by Zydus Cadila under the ZyCoV-D name. It is a DNA vial, the first of its kind in the world to be developed for humans, as until now it was only used in animals.

The DNA enters the nucleus, and there, the information is copied into a messenger RNA molecule, which in turn becomes the instructions to produce the Spike protein. In other words, it is an extra step in antigen production in the cell compared to mRNA vaccines, such as those from Pfizer or Moderna: while the latter did not require access to the nucleus to teach the cells to produce Spike, DNA vaccines did. 

The vaccine has completed phase I/II and phase III clinical trials, the latter involving more than 28,000 volunteers, 1,000 of whom were aged between 12 and 18. Provisional results, not yet published in any scientific journal (they have been made public by means of a press release from the developer), have shown 66.6% efficacy against symptomatic infection and 100% efficacy against the development of moderate disease. The release also states that there were no serious cases or deaths from covid-19 after administration of the second dose of the vaccine.

The injection will be the first being administered to minors in the country (up to 12 years), and is added to Pfizer, Moderna, Sinovac and Sinopharm formulas administered to children under 16 in the world.

The results of the first part of phase I/II trial, carried out on 48 adults between 18 and 54 years of age, did not record any severe side effects, according to the press release, and Dr. N. K. Arora, a senior member of the National COVID-19 Task Force, explained in the local newspaper The Hindu that "the response to the vaccine, that is, fever, pain, and feeling sick, is much lower than with the other vaccines currently used in India" (which include Moderna, Janssen, Astrazeneca, the local Covaxin, Covishield and Sputnik V). Neither the Indian government nor the developer itself has provided further details.

The main novelty of the drug, in addition to being the first DNA vaccine to face covid-19, relies in that it is administered by means of the Pharmajet applicator, which does not use a needle but 'injects' the contents of the vial through a fine, precise jet that penetrates the skin.

The vaccine is administered in three doses, each one 28 days apart from the previous one, and can be stored at temperatures between 2 and 8ºC, according to the developer in a press release, specifying that it remains stable at 25ºC for three months. The company explains that it has also requested approval for a two-dose version.