The primary outcome measure is neutralizing antibody levels specific to the Moderna or Pfizer vaccine at Week 48 after randomization. Comparisons will be evaluated using the ratio of geometric mean responses. Antibody levels will be log10 transformed and summarized with stratified analysis of covariance

The primary outcome measure is neutralizing antibody levels specific to the Moderna or Pfizer vaccine at Week 48 after randomization. Comparisons will be evaluated using the ratio of geometric mean responses. Antibody levels will be log10 transformed and summarized with stratified analysis of covariance