21 July 2020
India’s Covid-19 vaccine candidate
Source: The Indian Express
India’s top drug regulator, the Central Drugs Standard Control Organisation, has allowed Bharat Biotech India (BBIL) to conduct human clinical trials for ‘Covaxin’, making it the first indigenously developed Covid-19 vaccine candidate to receive this approval, the firm said. These trials are scheduled to start across India in July.
Covaxin is a vaccine candidate developed by BBIL against the novel coronavirus (Covid-19) in collaboration with the Indian Council of Medical Research’s National Institute of Virology (NIV).
As part of this collaboration, NIV isolated a strain of the virus from an asymptomatic Covid-19 patient and transferred it to BBIL early in May. The firm then used it to work on developing an “inactivated” vaccine–a vaccine that uses the dead virus–at its high containment facility in Hyderabad.
“Once the vaccine is injected into a human, it has no potential to infect or replicate, since it is a killed virus. It just serves to the immune system as a dead virus and mounts an antibody response towards the virus,” said the company, adding that inactivated vaccines usually have a better safety record.
BBIL’s Covaxin then underwent pre-clinical testing, which is when the vaccine is tested on animals like guinea pigs and mice to see if it is safe, before the firm approached CDSCO for approvals to move on to the next stage of testing–human trials.
The Drug Controller General of India, who heads CDSCO, has given Bharat Biotech approvals to begin testing its vaccines on humans through phase I and II clinical trials. This brings India a step closer to finalising a domestically developed Covid-19 vaccine for its population–a positive sign at a time when the country’s cases continue to surge, especially in the national capital.
The first phase, usually conducted on a small group of individuals, tries to find what dosage of the vaccine is safe for use, whether it is effective in building their immunity to the virus and whether there are any side effects. The second phase is conducted on a larger group comprising hundreds of persons fitting the description of those for whom the vaccine is intended using characteristics like age and sex. This phase tests how effective the vaccine is on the population group being studied.
Vaccines, like most new drugs, are meant to follow a clinical testing process spanning four stages, starting with pre-clinical tests and ending with phase III studies conducted on thousands of patients. After approval from the regulator, the firm has to continue monitoring the use of its vaccine on patients and submit post-marketing surveillance details, which checks for any long-term unintended adverse effects of the product.
Bharat Biotech plans to begin its phase I and II trials in July, but is unsure of the overall timeline for testing and approving its vaccine.
“At the moment we are not sure how the vaccine is going to perform in the humans, as clinical trials are about to commence. Based on the success results of phase I and phase II, we will progress to the larger clinical trials. Thereafter, the licensure timelines will be set out upon receiving regulatory approvals,” said BBIL.
Other Indian firms engaged in the development of Covid-19 vaccines include Zydus Cadila, Serum Institute of India and, since earlier this month, Panacea Biotec.
While Panacea is still in the pre-clinical stage, it is not clear whether Zydus and Serum have completed their preclinical studies and have also applied to CDSCO for approval to conduct human trials yet.
Covaxin has reached a more advanced stage of testing than two other vaccine candidates that Bharat Biotech is developing through global collaborations–the first is in collaboration with Thomas Jefferson University, while the second is with the University of Wisconsin-Madison and vaccine maker FluGen. Both these candidates are currently in the pre-clinical stage, according to the World Health Organisation’s draft landscape of Covid-19 candidate vaccines.
However, it is still far behind in the global race for a Covid-19 vaccine. AstraZeneca, whose vaccine candidate “ChAdOx1-S” with the University of Oxford is already at phase III trials, is the frontrunner. Serum Institute has an agreement to manufacture this vaccine.
Moderna, which is also close to beginning phase III trials for its LNP-encapsulated mRNA vaccine candidate with the National Institute of Allergy and Infectious Diseases, is close behind.
Apart from Covaxin, which is not listed among the vaccines being tried globally, at least six other candidates are in Phase I/II trials and another five are in Phase I trials globally.
Globally, Zydus Cadila’s DNA plasmid and measles vector vaccines as well as Serum’s codon deoptimised live attenuated vaccine, which it is developing with Codagenix, are still in the pre-clinical stage, according to WHO.