Vaccine development is complex process and takes 10 to 15 years --- I am not sure where you got this timeline of 2 years. From bench to a person's arm a vaccine development process normally takes 10 -15 years. Exploratory stage, preclinical, clinical and post-licensure monitoring of vaccines. It is a complex and expensive process and many vaccines fail in Phase I. The only reason COVID-19 vaccines had a short turn over was because it was an emergency and therefore regulatory authorities gave an EUA for these vaccines. Governments and biopharma had to chose the fastest and the most suitable vaccine candidate-not the best candidate (to get the best requires more time and research)

Source author: Sona Chowdhury sonachowdhury2014@gmail.com