This isn't a failure. This is the quickest vaccine rollout ever. The way you do statistics for this means that the overkill speeds up how quickly you can verify effectiveness. For example, if you do a booster after 6 months, that adds 6 months to your study time. If you try to thread the needle to make the smallest possible vaccine, you need way more testing to prove it works. The approach taken is why we have 10% of the US vaccinated now instead of having a vaccine approved in 2 years.