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India’s Covid-19 Vaccine Candidate, COVAXIN Explained

The covid-19 crisis is still going on throughout the world. It has affected over 11 Million people and leaving 527,835 people globally dead as per WHO reports on 5th July 2020.

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Amid Covid-19 crisis researchers have been working tirelessly for Covid-19 vaccine production. There are more than 200 candidates and only 15 have entered clinical trials globally.

In India, there are two possible Covid-19 vaccine candidates which are being cleared for clinical trials as per data on 4th July, 2020.

The Central Drugs Standard Control Organisation (CDSCO) has allowed Bharat Biotech International Limited (BBIL) to conduct Phase I and Phase II clinical trials for a vaccine candidate Covaxin or BBV152” on 29th June 2020, making it the first indigenously developed Covid-19 vaccine candidate to receive this approval.

The second candidate for Covid-19 vaccine of Zydus Cadila Healthcare Ltd named ZyCoV-D was also approved by the DCGI (Drug Controller General of India) for clinical trials.

What is Covaxin or BBV152?

As per reports, an inactivated COVID-19 vaccine candidate named Covaxin or BBV152 has been developed by Bharat Biotech International Ltd. in collaboration with ICMR – National Institute of Virology, Pune.

In early May, NIV isolated a strain of SARS-CoV-2 (novel Coronavirus 2019) from an asymptomatic patient and sent it to Bharat Biotech, to develop an “inactivated vaccine” which uses inactivated virus particles, produced at a high-containment facility (Bio-Safety Level 3) at Genome Valley, Hyderabad.

As this vaccine candidate is said to be a dead virus(inactivated virus ensures more safety), it can not replicate/multiply inside the host’s body once injected. However, it will act as an immunogen(activates immune system), further resulting in the production of antibodies specific for this virus.

If by any means, the same virus(in this case SARS-CoV-2 or novel Coronavirus 2019) tries to infect the body, the antibodies will destroy and neutralize the pathogen.

What is a Vaccine?

Vaccine uses an attenuated(weakened), killed, inactivated pathogen(virus, bacteria, or other microbes), associated proteins or genetic material to confer immunity to an individual by acting as an immunogen(antigen that activates the immune system and its components).

Once injected, it results in the production of antibodies specific for a particular virus. If the same pathogen tries to infect the host, it will be immediately destroyed by the immune system.

Understanding difference between vaccine and a drug for cure!

A drug for the cure of a particular disease is meant to be ingested by only an ill person whereas a vaccine is meant to be used by healthy people of different ages and sex(for everyone).

Thus, a vaccine undergoes a critical process of ensuring safety, effectiveness, and toxicity. This puts a great challenge to manufacture it and allow its use publicly only if deemed safe and effective.

When human clinical trials for ‘Covaxin’ will be conducted?

Preclinical testing report on guinea pigs and mice was found out to be safe.

Covaxin is said to enter phase I human clinical trials this month on 7th July and also to complete clinical trials and roll out for public use(if everything goes well) by 15th August, as per some reports.

According to a press release on 4th July 2020, ICMR stated,-

“ICMR’s process is exactly in accordance with the globally accepted norms to fast-track the vaccine development for diseases of pandemic potential wherein human and animal trials can continue in parallel.”

If this happens, it would set a world record of fastest vaccine production by mankind. This fast-track production and testing raise concerns over its safety among the scientific community as well as the public.

ICMR issued a statement regarding this concern by saying it is “cutting out unnecessary red tape, without bypassing any necessary process, and speed up recruitment of participants.”


Clinical trials outline for ‘COVAXIN’


According to data submitted to CTRI, subjects will be enrolled in three group of 125 individuals each.

Safety and immunogenicity evaluation will be done for 28 days and data submission to CDSCO(Central Drugs Standard Control Organization) post evaluation.


Random double-blind study

Subjects will be assigned to two groups randomly, one will receive the Covaxin whereas other would not, without their knowledge of who received what.

“A total of 750 healthy volunteers of age between ≥12 to ≤65 years will be enrolled in the study and vaccinated on day 0 and day 14, with a selected formulation based on the endpoints of Phase 1 study. Since the age group differs from the Phase 1, upon completion of the enrolment and vaccination of 50 participants in Cohort 1 and Cohort 2 as per randomization, safety assessment will be conducted seven days after vaccination,”- the trial registration document stated

Evaluation of immunogenicity will be done on Day 14, Day 28, Day 104 and Day 194 in two groups, having a total sample size of 1,125.

Other Covid-19 Vaccine candidate by Bharat Biotech

Bharat biotech is working in collaboration with the University of Wisconsin’s FluGen and Thomas Jefferson University to produce the Covid-19 vaccine, in addition of its collaboration with ICMR’s Covaxin.

BBIL is thus, currently working with three different institutions for the production of a possible Covid-19 vaccine.

Covid-19 Vaccine candidate by Zydus Cadila Healthcare Ltd named ‘ZyCoV-D’

Zydus’s ZyCoV-D also plans to enter clinical trials in July 2020 over 1000 subjects in India.

ZyCoV-D uses non-replicating and a non-integrating plasmid carrying the gene of interest(from SARS-CoV-2) and it is very safe. It requires a minimal biosafety lab (BSL-1) for the manufacturing of the vaccine.

With Plasmid used as a vaccine, it is easy to modify it in case the virus mutates. There are around 11 different strains of the novel coronavirus present in India.


 Other Indian companies involved in the development of Covid-19 vaccines include Serum Institute of India and Panacea Biotech (still in the pre-clinical stage).

Other Covid-19 Vaccine candidates throughout the world

The frontrunner is AstraZeneca, whose candidate ChAdOx1-S in partnership with the University of Oxford is at phase III of clinical trials. Serum Institute has an agreement for its manufacturing.

Other institutes like Moderna whose LNP-encapsulated mRNA vaccine candidate is close to phase III clinical trials in partnership with the US National Institute of Allergy and Infectious Diseases.

There are at least six other candidates which are in Phase I/II trials and another five are in Phase I trials globally.

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