Not an expert, but creating a perennial vaccine depends on the mutation rate and which highly-conserved regions can be targeted.
One of the potential vaccines enrolling trial patients is made of mRNA that codes for the spike protein needed for entry to cells. [0] If that spike protein turns out to be highly-conserved, then the vaccine will have sticking power. If it's not, but there turn out to be evolutionary trade-offs to adapting around it, it could push the virus to become less aggressive.
One of the potential vaccines enrolling trial patients is made of mRNA that codes for the spike protein needed for entry to cells. [0] If that spike protein turns out to be highly-conserved, then the vaccine will have sticking power. If it's not, but there turn out to be evolutionary trade-offs to adapting around it, it could push the virus to become less aggressive.
0. https://clinicaltrials.gov/ct2/show/NCT04283461