PROS1 and infection: Neutralizing antibody titers were measured with a pseudotypedvirus displaying S protein of SARS-CoV-2, and the highest dilutionto achieve infection of ≤ 90% or ≤ 99% was consideredthe NT90 and NT99 titer for the sample, respectively.S-specific CD8+ T cell numbers in the blood were quantifiedon days 10 and 28 using flow cytometry with the H-2kb S539–546 tetramer (Stet, gating method is shown in Figure S1).