The mRNA-1273 vaccine, jointly developed by the National Institute of Allergy and Infectious Diseases Vaccine Research Center and commercial biotech company Moderna, was the subject of an article in Nature.  The vaccine demonstrated stimulation of neutralizing antibodies in mice that were protected from subsequent infection with SARS-CoV-2.  The vaccine also elicited a  CD8 T-cell response, which is associated with persistence of immunity. Studies on laboratory animals, including nonhuman primates, correspond with successful phase-one clinical testing.  In human volunteers

It is significant that the vaccine was not associated with allergic inflammation termed vaccine-associated enhanced respiratory disease that occurred in the 1960s following administration of a respiratory syncytial virus vaccine.

Moderna was able to produce the mRNA-1273 vaccine within a short period based on previous experience developing a candidate MERS-CoV vaccine. 

*Corbett, K.S. et al. SARS-CoV-2 mRNA vaccine development enabled by protype pathogen preparedness, Nature DOI:10.1038/s41586-020-2622-0 [2020]