India has given emergency use authorization to a COVID-19 vaccine that uses circular strands of DNA, called plasmids, to prime the immune system against SARS-CoV-2. The vaccine, called ZyCoV-D, was developed by Indian pharmaceutical firm Zydus Cadila. It is the first DNA vaccine anywhere in the world to be authorized for human use.
In a trial of 28,000 participants, after three administrations, ZyCoV-D showed an efficacy of 67% against symptomatic COVID-19. Late-stage trial results have yet to be published. The advantage of plasmid DNA vaccines is that they are much simpler to manufacture than mRNA vaccines, and do not require storage at ultra-low temperatures.
