First DNA Covid Vaccine Found 67% Effective in Clinical Trials

India's Cadila Healthcare Ltd. has sought approval from the local drug regulator for its DNA-based vaccine against Covid-19 after the shot proved effective in clinical trials.

The drugmaker applied for emergency use authorization for the shot, which uses DNA to instruct the body's cells to produce proteins that spark a protective response, according to an exchange filing Thursday. The Phase 3 trials on more than 28,000 volunteers across 50 centers showed an efficacy rate of 67%, Cadila said. That is below the rates of the shots from Moderna Inc. and Pfizer-BioNTech that use messenger RNA technology.

Cadila, based in Ahmedabad, Gujarat, said the study was carried out "during the peak of second wave of Covid-19, reaffirming the vaccine's efficacy against the new mutant strains, especially the delta variant." However, it's not known if the researchers isolated and identified the strains that infected participants in the trial, nor has the company published the number of infections from which it derived the efficacy numbers.

The delta variant was first detected in India last October, triggering a devastating second wave there. It has since been found in almost 100 countries, complicating the U.K.'s reopening plans and forcing several Australian states to enter lockdowns.

Cadila plans to manufacture as many as 120 million doses annually of the shot, which requires three doses and is administered intradermally with a needle-free device developed by the company.

Tokyo-based AnGes Inc. and the U.S.'s Inovio Pharmaceuticals Inc. are among other companies working on DNA-based vaccines. Similar to mRNA technology, no DNA vaccine has been widely used against any disease thus far, but they are more stable and easier to store than mRNA shots.