Of course we can!
There is a field of study called statistics. Maybe you've heard of it.
If you know the rate of infection and death rate of those both with and without the vaccine then you can know quite well how many lives have been saved. Of course your sample size is important. I figure hundreds of millions of doses will do nicely in that regard.
No one, not one single solitary person, has EVER claimed that the vaccines are 100% effective. They are very clearly not 100% effective. They are in fact only about 90% effective.
There is no need for exact numbers and I STRONGLY suspect that you knew this when you wrote this post. This is, therefore, just one more example of how you are being intentionally deceptive. If you were stupid, you'd have something of an excuse. As it is, you're simply a liar. I cannot comprehend at all what in the world your motive could possibly be. You absolutely should be ashamed of yourself.
Clete