Why does COVID-19 vaccine may take more than a year?

Why does COVID-19 vaccine may take more than a year?

Last Reviewed : 12/16/2020
Why does COVID-19 vaccine may take more than a year?

Vaccination is inarguably the most cost-effective strategy to prevent infectious diseases. As COVID-19 spread all across the globe, every effort is made by research and development companies to accelerate COVID-19 vaccine production. With the serious global impact, every country is now waiting for COVID-19 vaccine to reduce the healthcare burden. Even with all the accelerated efforts, COVID-19 vaccine may not be available for more than a year.

According to a study published in PLOS ONE, a peer-reviewed journal, a database was compiled, including all human infectious disease vaccine projects from 1998 to 2009. On average, time taken for a vaccine from preclinical phase to market entry was 10.7 years. A vaccine has a market entry probability of 6%. It means that 94% of the vaccine projects may not even see the light.

Here are the several stages of vaccine development with their average timeline.

  1. Exploratory stage – approx. 2-4 years
  2. Preclinical stage – approx. 1-2 years
  3. Clinical development – approx. 3-4 years
  4. Regulatory review and approval – about a year
  5. Manufacturing – about a year
  6. Quality control

As of April 8, 2020, 115 COVID-19 vaccine candidates were identified. Seventy-eight were confirmed as active and thirty-seven were unconfirmed as development status could not be determined from available sources. Among 78 vaccine candidates, 73 are currently at early stages – exploratory and preclinical stages. The rest of 5 vaccine candidates moved into clinical development phase.

Clinical development has three phases. During Phase I, trial vaccine is administered to a small group of healthy people without underlying chronic health conditions. During Phase II, vaccine is given to people for whom the final new vaccine product is intended to be provided. For e.g., people from different age groups. In Phase III, vaccine is given to thousands of people and tested for safety. There is Phase IV which is usually initiated after the vaccine is approved and licensed.

Among all the stages, clinical development takes a significant amount of time. Administering the vaccine to thousands of people is crucial to test the safety profile. Without this phase, there may be detrimental consequences. The five COVID-19 vaccine candidates are in clinical development phase. If it is any other vaccine, it will take 5-6 years from here before entering the market.

Ebola vaccine took about five years total to get into the market. It took the shortest time for the development of a vaccine. With the extent of economic and global impact of COVID-19, emergency protocols are created to deliver the vaccine as soon as possible. COVID-19 vaccine entered clinical development phase only in two months after the genetic sequence of Novel Coronavirus is revealed. For any other vaccine, this would have taken 3-5 years.

At such an accelerated pace, COVID-19 vaccine is expected to defy all the red tape involved during the process of vaccine development. The U.S. Department of Health and Human Services (HHS) has a goal of delivering the vaccine by early 2021. With all the above extensive stages of vaccine development and regulatory approvals, this goal may be highly ambitious.



  1. Pronker et al. Risk in Vaccine Research and Development Quantified. March 20, 2013. https://doi.org/10.1371/journal.pone.0057755
  2. Tung Thanh Le et al. The COVID-19 vaccine development landscape. Nature Reviews Drug Discovery. April 9. doi: 10.1038/d41573-020-00073-5
  3. Singh et al. The clinical development process for a novel preventive vaccine: An overview. J Postgrad Med. 2016 Jan-Mar; 62(1): 4–11. doi: 10.4103/0022-3859.173187
  4. World Health Organization. Principles and considerations for adding a vaccine to a national immunization programme. From decision to implementation and monitoring.
  5. Centers for Disease Control and Prevention - vaccines and immunizations.

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