CFB and infection: 50 of the participants had high BA.1 or BA.5 neutralizing activity and 96.0% of those patients (48/50) had documented infection dates between December 1, 2021, and March 24, 2022, when the omicron BA.1 variant first appeared and quickly became the most prevalent variant in New York City (Fig. 3a & Supplementary Fig. 1a–c).