The general stages of the development cycle of a vaccine are:

  • Exploratory stage
  • Pre-clinical stage
  • Clinical development
  • Regulatory review and approval
  • Manufacturing
  • Quality control

Clinical development is a three-phase process. During Phase I, small groups of people receive the trial vaccine. In Phase II, the clinical study is expanded and vaccine is given to people who have characteristics (such as age and physical health) similar to those for whom the new vaccine is intended. In Phase III, the vaccine is given to thousands of people and tested for efficacy and safety. Many vaccines undergo Phase IV formal, ongoing studies after the vaccine is approved and licensed.


Research Institutes and pharma companies around the world have been endeavoring to develop a coronavirus vaccine. So far, there are over 155 potential candidates which are at the different stages of the development. Out of those, around 23 potential vaccines for Coronavirus are in the human trials. While, US, the UK, India, Russia, China, and Australia have been working on multiple potential candidates for COVID19 vaccine. Around the world, pharmaceutical companies have ramped up clinical trials in the past month. Gilead Sciences Inc’s remdesivir shows a positive efforts to treat the disease after it helped shorten hospital recovery times in a clinical trial.


  • Among the prime contender in the list is American pharmaceutical major, Moderna Inc. developed vaccine prototype, mRNA-1273. In what is being seen as positive news, the vaccine is set to start phase III trials will be conducted in 30,000 volunteers, considered to be the biggest and the most crucial one in the testing phase, from July 27. In the phase-I trial, the vaccine has been found to be safe and provoked a good immune response in the early testing done on volunteers.
  • AstraZeneca collaborating with a number of countries and multilateral organizations to make the University of Oxford’s vaccine widely accessible around the world in an equitable manner. A Phase I/II clinical trial began last month to assess safety, immunogenicity and efficacy in over 1,000 healthy volunteers aged 18 to 55 yearacross several trial centers in southern England. The licensing of the vaccine, formerly ChAdOx1 nCoV-19 and now known as AZD1222.
  • In a ray of hope, AIIMS, Patna has started human trials for COVAXIN, jointly developed by Bharat Biotech, Indian Council of Medical Research (ICMR), and National Institute of Virology, Pune.
  • Drug firm Zydus Cadila on Wednesday said it has started human clinical trials of its COVID-19 vaccine candidate ZyCoV-D. In the phase of trials, the company will be enrolling over 1,000 subjects across multiple clinical study sites in India.
  • Sinovac Biotech Ltd. (Beijing, China), a biopharmaceutical company, has stated that the company is 99% sure that its COVID-19 vaccine, called CoronaVac, will work. Sinovac has received approval from government authorities to conduct both Phase I and Phase II human clinical trials of its COVID-19 vaccine in China.
  • CanSino Biological Inc. and Beijing Institute of Biotechnology’s, Pennsylvania-based Inovio Pharmaceuticals’ vaccine candidates had gone up to phase I/ II of the trial.
  • Other vaccine candidates from Osaka University/ AnGes/Takara Bio/ Wuhan Institute of Biological Products/BioNTech/Fosun Pharma/Pfizer are currently in phase I/II of trials.

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