Bharat Biotech, which will soon be starting late-stage human trials of its Covid-19 vaccine on over 20,000 volunteers in India, is trying to ensure its candidate can improve clinical outcomes by at least 60 per cent. If it works, this vaccine — Covaxin — would be able to prevent at least 60 per cent of those inoculated from being clinically diagnosed with Covid-19.
This would be higher than the 50 per cent efficacy cut-off that the Indian drug regulator and various international counterparts have suggested would be enough for firms to meet in order for their Covid-19 vaccine to be considered successful. “What globally has been accepted by WHO and the US FDA (American regulator), MHRA (UK regulator) and our NRA (Indian drug regulator — CDSCO) is 50 per cent as the lower-bound efficacy cutoff. We are designing our trial for a 60 per cent efficacy cut off, so we are above what the NRA wants,” said Sai Prasad, executive director, Bharat Biotech. “But, again, the trial will tell us where we are,” he added.
“We have some inklings of efficacy from our animal challenge data in primates,” said Prasad. “We have now tested the neutralising antibodies from our vaccine against three or four circulating Covid-19 strains in India, and it protects against them, so that’s a good sign,” he said. “That means, even if there are any mutations to this virus, this vaccine will hopefully protect against it,” he added.
Even on the safety front, the early- and mid-stage testing on humans so far shows that the vaccine has not thrown up cause for concern, according to him.
“Our initial reactogenic events have been in that 10 to 15 per cent range, which is the norm when we compare it to all our other vaccines, We have not seen the high amount of SAEs (Serious Adverse Events) or reactogenic events compared to some of the other published vaccines that are out there, so we are very confident,” said Prasad.
The Central Drugs Standard Control Organisation (CDSCO), India’s top drug regulator, in September released guidelines that showed it would only approve Covid-19 vaccines that met parameters like their ability to show they could improve clinical outcomes by at least 50 per cent during human testing.
Bharat Biotech plans to test 25,000-26,000 volunteers in the third phase of its trials for Covaxin, which is expected to take place in sites across 12-14 states in India.
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