India’s first coronavirus disease (Covid-19) vaccine candidate Covaxin, which is being developed by Bharat Biotech, is likely to be at least 60% effective.
Late Thursday, the company received approval from the drugs controller general of India (DCGI) to conduct a Phase 3 clinical trial to establish the efficacy of their vaccine candidate. The interim results of the Phase 3 trial are likely to be released by April or May next year.
“The benchmark for the efficacy of our anti-Covid-19 vaccine is 60%. We will be conducting the largest Phase 3 trial for Covaxin, and the efficacy results should be available by early April-May, 2021,” Sai Prasad, executive director, Bharat Biotech International Ltd, told HT.
Prasad is a part of the product development team in Bharat Biotech.
World Health Organization (WHO) guidelines on the quality, safety and efficacy of respiratory syncytial virus vaccines approves of a vaccine with at least 50% efficacy.
“The WHO, US FDA (Food and Drug Administration) and even India’s Central Drugs Standard Control Organisation (CDSCO) approve a respiratory vaccine if it achieves 50% efficacy; for Covaxin, we aim to achieve at least 60%, but it could also be more. Chances of the vaccine being less than 50% effective are remote, as suggested by our trial results so far, which include results from animal studies,” Prasad said.
As per the current plan, the Phase 3 trial to determine vaccine efficacy will begin early to mid-November with 26,000 study subjects at 25 to 30 sites across 13-14 states. For the Phase 1 trial, the company recruited 375 subjects, and in Phase 2, 400 subjects participated.
“We have begun site preparatory exercises for Phase 3; recruitment and dosage will begin in November. The trial will provide two doses each for the vaccine and placebo recipients. Site selection and recruitment depend on several factors such as attack rate, how the disease spreads locally, etc. About 2,000 subjects could be enrolled per hospital,” said Prasad.
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Bharat Biotech has completed the Phase 1 trial, and submitted the results to DCGI. The results did not flag any major safety concern. For Phase 2, the safety test has been completed, and the immunogenicity test (to check the body’s immune response to the vaccine), is currently underway.
“The follow-up for determining the immunogenicity of a vaccine candidate takes longer—about a month or two. The interim data for Phase 2 will come out in November,” said Prasad.
Covaxin has been developed in collaboration with the Indian Council of Medical Research (ICMR) – National Institute of Virology (NIV) using inactivated Sars-Cov-2, the virus that causes Covid-19. The virus was isolated in an ICMR lab.
According to experts, a lot would depend on the Phase 3 trial results. “Because of the large sample size for the Phase 3 clinical trial, its results will be crucial to determine whether the vaccine would work. Phase 1/2 trials show promise, while Phase 3 is all about performance,” said Dr K Srinath Reddy, founder, Public Health Foundation of India.
The company is looking at a production capacity of about 150 million doses annually. However, the cost of the vaccine is yet to be decided. “Pricing isn’t decided yet as we are still looking at the cost of product development. For the Phase 3 clinical trial, we will spend about Rs 150 crore in the next six months,” said Prasad.
