On Dec. 3, 2020, Moderna announced in a letter to the editor published in the New England Journal of Medicine reporting that participants in the Phase 1 study of mRNA-1273, its COVID-19 vaccine candidate, retained high levels of neutralizing antibodies through 119 days following first vaccination (90 days following second vaccination).

The study was led by the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health (NIH).