article on work that is being pursued to address such an occurrence...i.e. an 'All-in-One' vaccine...I've also heard that our DARPA program is working on the same objective...not sure if they are coordinating or actually part of the same effort.
This information is also useful for those who want to prepare themselves for arguing against any vaccine that may be offered to the public...no time like the present.
Link: https://www.nih.gov/news-events/nih-research-matters/fighting-current-future-coronaviruses-single-vaccine