In reply to Yanis Nayu:
There are several steps that I can see needing to happen. Some of these can be concurrent.
1. Understand the immunity involved (is it protective, partially protective or in some instances harmful)
2. Understand the evolution of the virus - is it going to change (antigenic drift / shift) making vaccines difficult to make or needing to be revised perhaps every year
3. Identify antigens that you can put in a bottle that give you protective immunity without giving you the disease
4. Ensure that the vaccine is safe (i.e. doesn't cause immediate signs or when you encounter this or another coronavirus)
5. Ensure that the vaccine works