Written By: Chad Hensel, PT, DPT, MHS, CSCS

With the world holding its collective breath for the announcement of a COVID-19 vaccine, this is a good opportunity to shine the spotlight on the typical drug approval process of the F.D.A. 

One of the main roles of the Food and Drug Administration is approving drugs (including vaccines) and ensuring public safety. 


This process has many steps:

  • Initially, a drug undergoes “preclinical trials” that are typically conducted in a lab and/or with animals. This process can last about 1-2 years.
  • If a drug successfully makes it out of preclinical trials phase and it is showing good data, the drug will receive the green light and will move to clinical trials (human trials).
  • Clinical Trial Phase 1: Typically conducted on about 20-40 healthy subjects — these subjects do not have the targeted disease being studied.  Phase 1 normally lasts less than one year. The focus of Phase 1 is safety. If successful, the drug is moved to Phase 2.
  • Clinical Trial Phase 2: In this phase, the effects on the subjects with the targeted disease are looked at. These will be controlled trials and usually involve 50-300 subjects.  The focus of this phase is effectiveness and it can last up to 2 years. If successful, the drug will move on to Phase 3.
  • Clinical Trial Phase 3: This is a large-scale trial in which thousands of subjects are used from a variety of backgrounds and geographical locations. This stage is the most important to establish safety and effectiveness. If this phase is successful, the FDA may grant this drug approved. This phase normally can run up to 3 years.


As you can see, this process is normally not a fast one.  Only in times of a public health crisis (which we are in now), are when the FDA grants expedited studies and accelerated approvals. With several vaccine trials now in Phase 3—it all comes down to the data…



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Ciccone CD. Pharmacology in rehabilitation. 5th edition, Philadelphia, FA DAVIS 2016.