Zydus Cadila begins human trials for its Covid-19 vaccine candidate

A health worker collects a swab for Covid-19 test, in Kolkata on Monday. Photo: ANI
The human trials for an indigenous Covid-19 vaccine are closer to the finishing line. 

On Wednesday, Ahmedabad-based Zydus Cadila said it has commenced human trials (Phase 1 and 2) for its deoxyribonucleic acid (DNA) plasmid vaccine ZyCoV-D. 

Meanwhile, Bharat Biotech’s Covaxin human trials, too, have begun. According to the Clinical Trials Registry-India, the estimated timeline for Covaxin trials (Phase 1 and 2) is one year and three moths. Experts feel it will be sooner than estimated.

Panacea Biotec is working on an inactivated whole virus vaccine candidate. Its Managing Director Rajesh Jain said the global generic and specialty pharmaceutical and vaccine maker aims to start human trials in September this year. 

Multiple vaccine candidates are expected to get cleared by the drug regulator in the first quarter of 2021.

As for ZyCoV-D, developed in the Vaccine Technology Centre in Ahmedabad, pre-clinical studies were done on multiple animal species like mice, rats, guinea pigs, and rabbits. “The antibodies produced by the vaccine were able to neutralise the wild type virus in virus neutralisation assay, indicating the protective potential of the vaccine candidate,” said the global health care provider. 

Zydus claimed no safety concerns were observed for the vaccine candidate in repeat dose toxicology studies by both intramuscular and intradermal routes of administration. In rabbits, up to three times the intended human dose was found to be safe, well tolerated, and immunogenic, it added. Phase 1 and 2 trials will be on 1,000 volunteers. 

But what is a DNA plasmid vaccine? It is a relatively new vaccine technology. It is considered cost-effective for scaling up. Cells have DNAs in their chromosomes, and outside the chromosomes in a form called plasmids. Scientists insert the virus genetic material into such plasmids they have obtained from bacteria. The plasmid is then inserted into the body. This triggers an immune response. 
Speaking about the vaccine candidate, Pankaj R Patel, chairman of Zydus Cadila, said it has started work in March and it will take three months to complete Phase 1 and 2 trials. Based on the data from trials, the company will approach the drug regulator for a nod for Phase 3, which will take place on at least 5,000 volunteers. Patel felt the Phase 3 trial will take a minimum of three months if all goes well. 

Zydus has a team of 60 people for in-house clinical trials. They are actively working with the trial sites. 

Senior virologist Jacob John had said it will take a minimum of three months to complete Phase 1 and 2 trials if one does not lose a single day in the intervening period. 

Human trials begin with Phase 1, which involve giving vaccines to volunteers with informed consent and look for potential adverse effects. There are two kinds of adverse effects — any toxic effect on any human body tissue (picked up by symptoms or biochemical parameters in blood), and check if one develops any adverse immune reaction. Phase 2 then checks the dosage and has two arms or more. In one, people are given a single dose and in others, people are given two doses or more. 

Experts feel after the safety profile of a vaccine candidate is established (after Phase 2), volunteer recruitment may be easy for Phase 3. 

The World Health Organization (WHO) is tracking the vaccine projects of Zydus. Some of the global vaccine candidates that WHO finds promising are being tracked by the agency.

Fully indigenous pneumonia vaccine gets DCGI nod

The Drug Controller General of India gave its approval for the first fully indigenously developed pneumococcal polysaccharide conjugate vaccine (PPSV23) developed by the Serum Institute of India.

The trials have been conducted in India and Gambia.  The Special Expert Committee (SEC) for vaccines has reviewed the clinical trial data. The SEC recommended for grant of permission of market authorisation for the vaccine.

The government noted that earlier the demand for such a vaccine was substantially met by licenced importers in the country since manufacturers were all vaccine companies based outside India.

This vaccine is used for active immunisation against invasive diseases and pneumonia caused by streptococcus pneumonia in infants. The vaccine is administered in an intramuscular manner. SOHINI DAS

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