People seem to forget that we launched all of these vaccine types simultaneously because we were terrified that NONE would work.
The only reason we can sit here and armchair quarterback the AstraZenca vaccine is because we actually got really lucky and have a plethora of functional vaccines.
Had you told medical researchers 12 months ago that by March 2021 we would have a half-dozen Covid vaccines and we would have multiple ones at 95%+, they would have told you that you were delusional.