That's not really true. The phase 1 trials were a good bit faster than they'd normally be. Also, even if you ignore that, having years of phase 2 and phase 3 tr

That's not really true. The phase 1 trials were a good bit faster than they'd normally be. Also, even if you ignore that, having years of phase 2 and phase 3 trials gives you a lot of additional safety data, in the form of larger trials with longer duration. Also, better cross-tabs, so that it's possible to assess safety by age, gender, race, pregnancy, etc. The vaccine trials were limited in their power to detect rare events. The Pfizer trial [1], for example, explicitly said that events rarer than 0.01% are less likely to be detected: > This trial and its preliminary report have several limitations. With approximately 19,000 participants per group in the subset of participants with a median follow-up time of 2 months after the second dose, the study has more than 83% probability of detecting at least one adverse event, if the true incidence is 0.01%, but it is not large enough to detect less common adverse events reliably. This report includes 2 months of follow-up after the second dose of vaccine for half the trial participants and up to 14 weeks’ maximum follow-up for a smaller subset. Therefore, both the occurrence of adverse events more than 2 to 3.5 months after the second dose and more comprehensive information on the duration of protection remain to be determined. Although the study was designed to follow participants for safety and efficacy for 2 years after the second dose, given the high vaccine efficacy, ethical and practical barriers prevent following placebo recipients for 2 years without offering active immunization, once the vaccine is approved by regulators and recommended by public health authorities. Assessment of long-term safety and efficacy for this vaccine will occur, but it cannot be in the context of maintaining a placebo group for the planned follow-up period of 2 years after the second dose. Even a 0.001% risk is not small, when you're talking about giving the vaccines to billions of people. (I don't mean to single out Pfizer here. It's just the one I've read most recently.) [1] https://www.nejm.org/doi/full/10.1056/nejmoa2034577 https://www.nejm.org/doi/full/10.1056/nejmoa2034577