That isn't how the immune system works. It's not a binary gate that's either open or closed. It's more like a war between two armies, and it depends on which si

That isn't how the immune system works. It's not a binary gate that's either open or closed. It's more like a war between two armies, and it depends on which side musters the larger army and how creatively the armies fight. If the vaccine reduces chance of infection, it will also reduce severity, because both operate via the same mechanism: antibodies killing the virus.