What are the chances that sars-covid-2 changes and develops much like the seasonal flu? If a vaccine is developed for sars-covid-2 would the composition of the vaccine need to be changed like the one required to protect against the seasonal flu?
no one knows if this will become seasonal. SARS did not; MERS is very limited. If a vaccine is made that attacks a non-mutating portion of the virus, then composition probably would not have to change, but if virus mutates, yes, vaccine would have to change.