Dr Reddy's Labs denied approval for final trial of Russian-made Sputnik Light

India's drug regulator on Wednesday denied permission to Hyderabad-based Dr Reddy's to conduct phase-3 trials on the Russian vaccine Sputnik Light in India.

The subject expert committee (SEC), a body under the drug regulator, did not find any "scientific rationale" to conduct phase-3 trials and hence did not consider Dr Reddy's application seeking to carry out trials in India, according to sources familiar with the matter.

The application was taken up for discussion on Wednesday. Sputnik Light is a single-dose vaccine.

After launching Sputnik V, Russia introduced a new single-dose vaccine, called Sputnik Light, in May. As in the case of Sputnik, Sputnik Light has also been developed by the Russian ministry of health, the Gamaleya National Research Centre of Epidemiology and Microbiology and the Russian Direct Investment Fund (RDIF).

Sputnik V is a two-dose vaccine made from two components - recombinant adenovirus 26 or Ad26 and adenovirus 5 or Ad5 The first dose (Ad26) is the main vaccine, and the second (Ad5) is a booster shot. The Sputnik Light vaccine is made from Ad26, which is the first part of the Sputnik V vaccine.

"Sputnik Light is nothing but just the first dose of Sputnik V. Dr Reddy's wanted to test immunogenicity, (the extent to which the vaccine can teach the immune system to counter the virus). As a result of the earlier trials on Sputnik V, the immunogenicity data on both the doses (components) was seen. The data with single dose vaccine was not so great and hence the SEC did not find any rationale to conduct the trial again," said a source.

India so far has mainly been using two vaccines - Covishield and Covaxin - in its vaccination drive.

In May, Dr Reddy's launched the third vaccine - Sputnik V.