In Phase III, the drug is given to many people to study its effectiveness and safety.


New Delhi: In the global race to find a vaccine for the prevention of the deadly SARS-CoV2 virus, there are at least seven candidates who have reached phase III clinical trial of different vaccines across the world.

Phase III in clinical trial is the phase in which the drug is administered to a large number of people to expand the scope of its study for effectiveness and safety of the drug. The next step, if the trial is successful, is to apply for necessary permission from drug controllers and start the commercial production of the vaccine or the drug.

The top seven candidates in the race to find a vaccine for Covid-19 include Moderna’s mRNA-1273 vaccine, University of Oxford and AstraZenca’s Covishield, SinoVac’s CoronaVac, Sinopharm’s inactivated vaccine, Russia’s Sputnik, Pfizer and BioNtech’s BNT 162 and Chinese CanSino Biologic’s Ad5-nCoV.


In January, Moderna started developing a vaccine for developing antibodies in the human body to fight the Covid-19 virus. Moderna is developing this vaccine based on Messenger RNA called mRNA to produce viral proteins in the human body which will help the body to produce antibodies that will prevent one from catching the Covid-19 infection.

The vaccine produced by Moderna had shown good results in monkeys against the coronavirus and was first inducted into human trials in March this year, yielding promising results. Moderna is currently conducting phase III trials across the United States and has recruited 30,000 healthy people who are being administered the shots of this vaccine. The research team is going to observe the candidates over a period of time. This vaccine is being co-developed by the Cambridge, Massachusetts-based biotechnology company Moderna, Inc., and the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health.

CanSino Biologics

CanSino Biologics, a Chinese company, is developing a vaccine called Ad5-nCoV, based on Adenovirus known as Ad5, which is a common cold virus. This vaccine is currently under Phase III of the clinical trial and the Chinese military is presently using this vaccine to vaccinate its soldiers. The Phase I clinical trial of the virus which was completed in May this year has delivered promising results after which phase II clinical trial was undertaken. The company in July had reported that the vaccine was demonstrating promising results and had produced strong immune response in the candidates who were administered this vaccine. After promising results of the vaccine, Saudi Arabia on 9 August had announced that this vaccine would be used in Phase III of clinical trial in their country and later, even Pakistan joined in to host Phase III trial of this vaccine in their country.

CanSino Biologics is developing this vaccine in association with the Institute of Biology in China’s Academy of Military Medical Sciences. The Tongi Hospital in Wuhan is also the hospital associated with the trails of this vaccine.

AstraZeneca and University of Oxford

ChAdOx1 or the Covishield is a vaccine that is being developed jointly by the University of Oxford, Indian Serum Institute and the British-Swedish Company AstraZeneca. This vaccine is currently under Phase III of clinical trial and they have recruited thousands of healthy individuals in countries like the UK, India, Brazil and the United States. The Phase II study of this vaccine has proved to be efficient in producing immune response in humans.

Currently, global trials of this vaccine were halted on 8 September, after a patient who was administered this vaccine had reportedly fallen ill. The ChAdOx1 nCoV-19 is made from a virus (ChAdOx1), which is a weakened version of a common cold virus (adenovirus) that causes infections in chimpanzees, that has been genetically changed so that it is impossible for it to grow in humans. The vaccination aims at making the body recognise and develop an immune response to the Spike protein that will help stop the SARS-CoV-2 virus from entering human cells and, therefore, prevent infection.

Once the vaccine completes its clinical trial, the company has said that they would be able to manufacture and deliver at least two billion doses in record time. The company has also said that if the trail is successful, they would also be able to manufacture doses as early as October this year. The Indian Institute of Serum has also already produced millions of doses which are to be administered in the trial.

Russian Sputnik V

Sputnik V is a vaccine which is being developed by The Gamaleya Research Institute, part of Russia’s Ministry of Health. This vaccine is a combination of two adenoviruses Ad5 and Ad26 and both of these have been engineered with a coronavirus gene to produce immune responses in humans to protect them against the Covid-19 virus.

The Russian Institute had launched the clinical trial in June this year and by August, the institute had already begun phase III trials. This had led to a controversy in the medical fraternity about the efficacy of this vaccine, after which the results for Phase I and II trials were published on 4 September. The study of the results conducted on a small number of people showed that the vaccine produced immune response in the candidates with mild side effects. The vaccine’s phase III trials are currently underway and it is being administered to over 40,000 people.


The CoronaVac is a vaccine which is being developed and produced by a private Chinese firm, SinoVac Biotech. CoronaVac, which is presently in Phase III of clinical trial, is an inactivated vaccine which means that the company had developed the coronavirus in a laboratory in a controlled setting and had later killed it, making the pathogen inactivated. This vaccine when injected into a healthy human is expected to produce immune response against the Covid-19 virus. The phase I and Phase II trial of this vaccine have shown good immune response in older candidates of the age 60 years and above. The Phase III trial of this vaccine was launched in July and is presently underway in Brazil and Indonesia.


SinoPharm is also working on developing a vaccine based on the Inactivated model of the vaccine on the lines of the Sinovac vaccine. This inactivated vaccine is presently under phase III of clinical trial and is being tested in about 5,000 candidates in the United Arab Emirates. SinoPharm is developing this vaccine in association with the Beijing Institute of Biological Products. The vaccine is likely to be made available if positive outcome is reached in the Phase III trials by early next year.

India also has at least two frontrunner candidates in the global race for finding a vaccine against the coronavirus. The two Indian vaccines–ZyCov-D by Zydus Cadila and Bharat Biotech’s Covaxin, is also in this race. Both these candidates are currently in phase II of the clinical trial.

ZyCov-D by Zydus Cadila, which is developed using a genetically engineered DNA molecule coded with the DNA sequence of the SARS-CoV-2 virus, has shown good immune response in candidates who were administered this vaccine shots. Bharat Biotech’s Covaxin is a form of an inactivated vaccine which is developed by killing the SARS-CoV2 virus in a laboratory and then injecting it into the human body, activating the body’s immune response against the virus and thus creating antibodies for the virus. This has also reportedly shown good immune response to the candidates in the trials done so far.