[gizmo686]

Due to lack of need. Creating vaccines for the common human strains of corrona virus would be spending a lot of effort to stop the common cold (possibly including a flu like seaaonal vaccine).

Work on SARS resulted in cadidate vaccines, but was abonded before human trials because of succsefull containment.

Work on MERS resulted in a vaccine that is currently showing succsess in humans.

Work on SARS-COVID-2 is starting from those, and already has canditate vaccines based on modifying ones we know showed signs of success against other corona virus.

Maybe this will turn out to be another HIV, where a virus proves ellusive, but I haven't seen anything to suggest that.