Fig. 1: Study profile.

*Participants who were administered the vaccination and completed all safety visits, but did not have blood samples taken upon personal request. †290 participants who showed negative neutralizing activity against the wild-type strain or who refused to undergo testing the neutralization assay against multiple variants on day 28 after the second dose were excluded. ‡361 participants with negative neutralizing activity against the wild-type strain on day 180 after the second dose were excluded.