I am aware the sample sizes of participants they tested on were very large. But all that can be studied over a span of a few months is short term safety and efficacy.You seem intelligent, although not Intelligent enough to ever discipline me. Anyway, I think that you are confusing the amount of time it generally takes to complete stage 3 trials with the amount of money it generally takes to complete them. An unprecedented amount of money was spent on this
Even with all the money and participants in the world it still doesn't give anyone any idea of what can be said for long term safety and efficacy for the vaccines. Only time will tell. Hence why stage 3 trials typically last several years.