A four-fold increase in neutralizing titers was also significantly associated with protection from symptomatic BA.1 infection: 28% protection (95% Confidence Interval [CI] 12–42%) for BA.1 neutralizing titers, 28% (CI 12–42%) for BA.2 neutralizing titers, and 28% (CI 7–44%) for D614G neutralizing titers. Here, CFB is linked to infection.