PROS1 and COVID-19: The magnitude and breadth of the pre-dose 1 (D1) and post-dose 2 (D2) IgG responses to SARS-CoV-2 S protein were assessed in plasma samples collected from Cohort 1 IA patients from March 2021 to July 2021, which corresponded with the Delta and early Omicron COVID-19 waves (19).