This is a phase 2a, open-label study enrolling up to 106 healthy adults that participated in Study ARCT-021-01 (the Parent Study). Participants will enter this study approximately 3 months after their final study visit in the Parent Study. Participants that received placebo in the Parent Study or who are seronegative for SARS-CoV-2 neutralizing antibodies at screening will receive a single dose of ARCT-021 and will be followed for 365 days. Participants that received two injections of ARCT-021 in the Parent Study will not receive any further injections of ARCT-021 and will be followed for 281 days.
This is an open-label study enrolling healthy adults that participated in Study ARCT-021-01 (the Parent Study). Participants will receive either a single injection of ARCT-021 or no injection and be followed for up to 365 days.