The Front-Runners Of Vaccine

Arunima Basu

13th September, 2020

We all know that the world today is facing a huge threat from an invisible enemy i.e. the novel coronavirus-19, which has shut all of us indoors. Nevertheless, the situation always improves. In this case, the various vaccine trials all over the world have provided us with a streak of hope. In the present day, there are more than 150 vaccine candidates worldwide. Researchers have now reported data from the early clinical trial of a few candidates of the Covid-19 vaccine. So far, the result is positive and the vaccines appear to be generally safe and they spur immune responses against the novel coronavirus (Bureau, N. (2020, July 23). Meet the 4 frontrunners in the COVID-19 vaccine race. Retrieved September 10, 2020, from

But, are these immune responses enough to protect people from the infection and disease? Well, let’s hope for the best.

Now, let’s take a closer look at each one of the vaccines produced to date.


  • mRNA-1273: Moderna, NIAID.


This mRNA or messenger RNA vaccine made by the biotech company Moderna is working with the National Institute of Allergy and Infectious Diseases. The idea behind the mRNA vaccine platform is that it delivers a brief extract of a target virus’s genetic code- in this case, code in the form of mRNA- into human cells. Those cells can then translate that code into viral protein. From there, the immune system can send a response to the protein, which can be activated if the target virus ever tries to invade. In this case of mRNA-1273, researchers used a fatty nanoparticle to package up mRNA that codes for the SARS-CoV-2 spike protein. The vaccine candidate had shown promising results in primary safety trials. However, some side effects were observed in later dosages

  • AZD1222 (ChAdOX1 nCoV-19): Oxford University, Astrazeneca.


AZD1222 is a vaccine made from the weakened version of a common cold virus that causes infections in chimpanzees and has been genetically changed so that it cannot grow in humans (Carlson, R. (2020, September 10). AZD1222 SARS-CoV-2 Vaccine. Retrieved September 10, 2020, from

Genetic material has been added to the ChAdOx1 virus, which is then used to make proteins from the SARS-CoV-2 coronavirus called spike glycoprotein. The protein is usually found on the surface of SARS-CoV-2 and plays an essential role in the infection pathway of SARS-CoV-2. Researchers can package proteins of a dangerous virus into a far less dangerous one using this platform. The SARS-CoV-2 coronavirus uses its spike protein to bind to the ACE-2 receptors on human cells and cause infection (2020, March 10. Novel coronavirus structure reveals targets for vaccines and treatments. Retrieved September 10, 2020, from


By vaccinating, the researchers are hoping to make the body recognize and develop an immune response to the spike protein that will help to stop the virus from entering the human cells and prevent infection. The vaccine has recently entered the third phase trial after showing a safe and positive immune response in the body in the first and second phases of the trial. (Kunzmann, K. (2020, April 29). COVID-19 Vaccine Trial Underway in England. Retrieved September 10, 2020, from

  • Ad5-vectored COVID-19: CanSino, Chinese military.


Like AZD1222, CanSino uses a viral-based vaccine based on weakened adenovirus. Interestingly, the adenovirus used is not the one that is present in chimpanzees but humans. After a successful second phase trial, now, they are planning to enter the phase 3 trial.

  • BNT162b1: BioNTech Pfizer.


It is an mRNA based vaccine made by German firm BioNTech and the pharmaceutical giant Pfizer. It is a lipid nanoparticle formulated, nucleoside- modified mRNA vaccine that encodes trimerized SARS-CoV-2 spike glycoprotein receptor-binding domain. It too is showing positive responses like the other vaccines.

  • Sputnik V: Russia.


Developed by Moskow's Gamaleya Institute, this vaccine is already approved conditionally by the Russian government and is going to be tested on 40,000 citizens. Surprisingly, approval came even without phase 3 trials. The vaccine had only undergone accelerated phase 1 and phase 2 human trials and now facing global criticisms for inadequate testings. Russia got a head start because its MERS vaccine was ready. COVID-19 is 80% similar to MERS and is based on the already existing human adenoviral-vector platform where inactivated adenoviruses act as vectors delivering genetic material from S-protein, which forms the spike of coronavirus into a human cell to induce an immune response.

  • COVAXIN: Bharat Biotech in collaboration with the Indian Council of Medical Research and National Institute of Virology.


This is purely an Indian venture and has successfully entered into phase 2 human trials. It has been developed by using an inactive version of the spike protein of the novel coronavirus and aims to trigger an immune response in the human body with the production of protective antibodies.

  • ZyCoV-D: India


Zydus Cadila has launched phase 2 clinical trials of its COVID-19 vaccine candidate, ZyCoV-D which showed promise in phase 1 human study. It is a plasmid DNA vaccine. DNA vaccines use genetically engineered plasmids- a type of DNA molecule integrated with the antigenic protein encoded by DNA, against which the immune response is to be built. The DNA sequence injected would match that of the virus helping the body build antibodies against it.

How long will these trials continue?

Generally, the first phase human trials of all vaccines take over a month to 3 months to complete. Moving on to phase 2 trials it takes nearly 2-3 months and, in some cases, it may take around 15 months to complete. The phase 3 trial is most crucial and must be tested at least on thousands of randomly chosen healthy volunteers and it may take 3-4 months.

About the Author

AirBrush_20200821132647 - Arunima Basu.j

Arunima is currently majoring in biotechnology. She likes keeping herself updated about various interesting topics of science and technology. Apart from that, writing on such varied topics has always been one of her hobbies.