The nucleocapsid is inside the live virus - it's not accessible from the outside. So we don't currently know of a way to train the human immune system to bind t

The nucleocapsid is inside the live virus - it's not accessible from the outside. So we don't currently know of a way to train the human immune system to bind to it to kill live virus particles. So while it's important to understand the role of the nucleocapsid in infectivity, it's not actionable for vaccine technology. Conversely, there is currently no evidence that the spike can be "highly compromised" without reducing infectivity. The spike has to bind specifically to ACE2 in order to enter the cell. As long as that's true, vaccines can continue to target live virus using the ACE2 receptor binding domain in the spike protein.