To be pedantic, that would not be a vaccine, that would be an anti-viral drug. What they were doing here is expressing parts of the actual corona virus antigens

To be pedantic, that would not be a vaccine, that would be an anti-viral drug. What they were doing here is expressing parts of the actual corona virus antigens on a "baseplate" that could contain many copies of it, in the hope that the human immune system would catch up on it if presented to the body and the resulting antibodies would possibly be effective against the coronavirus. Regarding antiviral drugs for this, the corona-virus entry mechanism was elucidated and candidate inhibitors for this were located in previous articles during the last week ( https://www.cell.com/cell/fulltext/S0092-8674(20)30229-4 https://www.cell.com/cell/fulltext/S0092-8674(20)30229-4 )